FAQs about Ariid Catfishes, aka Columbian, Silver-Tipped-... "Sharks" Compatibility Related Articles: Marine, Brackish & Freshwater Catfishes (Columbian, Silver-Tipped, Black Fin... "Sharks") of the Family Ariidae by Bob Fenner, Columbian Shark Catfishes and other Ariidae by Neale Monks, Related FAQs: Ariid Cats 1, Ariid Cats 2, Ariid ID, Ariid Behavior, Ariid Selection, Ariid Systems, Ariid Feeding, Ariid Disease, Ariid Reproduction, Marine Catfishes, Catfishes in General,

Ragged Angelfish Fins, beaten       8/18/12 Hello all!  I am a novice fish enthusiast and am having trouble. I have searched the website and it has terrific information, but I am really wanting to have confirmation on what is going on with my tank.  I started out at my locally owned fish store and bought a 20 gallon tall tank, had many difficulties with cycling and losing fish, and also with the types of fish I was keeping together.  I was ready to throw the towel in when I found an out of town pet store, family owned, not the big box store, that helped me greatly! <Good.> Sorry for the tout but I feel its very important for people to realize the difference in a place looking to earn a buck and a place that is concerned with educating its customers.  Anyhow, after the cycling problems, I emptied the tank completely, left the rocks unwashed, and refilled and since my water quality has been greatly improved.  That was two months ago.  I am using a Aqueon on the tank filter with a carbon insert, <Carbon is largely useless in your sort of aquarium; instead, concentrate on biological media. Remove the carbon and replace with filter floss or sponge or ceramic noodles.> and a Terra Easy Strip tester kit.  According to the tester strips my Nitrate is just below 20, I assume this because the color it turns is slightly less pink than the color it should be if it is 20ppm, Nitrite is 0, Hardness is 150 GH ppm, Alkalinity is 80 KH ppm, and pH is 6.8. <All sounds fine for Angelfish.> I am thinking I need to invest in a good quality vial test kit, and wonder which one is worth my investment. <Possibly; I use the strips and they're quick and easy. But as/when they run out, and you really want the accuracy liquid test kits provide, be sure to get a nitrite test kit and a pH test kit, as these give you the best "quick look" tests for water quality and water chemistry.> Onto my fish problem.  Once I felt my tank had stabilized I ended up with 4 small juvenile Angelfish, 2 Pictus Cats, <These are restless, predatory fish that do better in schools and need much more space than 20 gallons (and to make matters worse, a "tall" 20 gallon tank provides even less swimming space than a plain vanilla 20 gallon tank!)> 2 White Tip Sharks, <Do you mean the catfish? What used to be called "Arius jordani" but is properly called Ariopsis seemanni? You do understand this isn't a freshwater fish? It needs brackish conditions when young, and preferably marine conditions as an adult. Even in a 20-gallon marine aquarium you wouldn't keep these catfish -- they get HUGE, easily 20-30 cm/8-12 inches, and sometimes a bit more than that.> and one algae eater. <What sort of "algae eater"? A common Plec, i.e., a Pterygoplichthys species of some sort? Again, a huge fish -- 30 cm/12 inches within the first year, and 45 cm/18 inches within two; barely viable in a 55 gallon aquarium, and really needs 75-100 gallons unless you happen to like murky, faeces-ridden aquaria. Trust me, if defecating were an Olympic sport, Plecs would win the gold!> Everyone seemed very happy and I was doing 20% water changes every week to week and a half.  After about a month I noticed one morning that one of my Angelfish was barely swimming on its side near the bottom of the tank, it died later that day.  Within 48 hours I lost a total of 3 angels to this problem.  They still looked healthy except for some ragged fins.  The one pictured attached had ragged fins but persevered and other than the fins was acting normally.  I did a 50% water change and tested the water before and after and the water did have a low level (.5) of Nitrate, after the water change, none.  Since then the survivor seemed to be doing well, eating vigorously, but his rear fin hasn't grown back, and his top fin is ragged this morning.  I checked the water quality and those are the stats I gave you above. <I don't trust those values. It's not necessarily the test kit is inaccurate (though dip strips are, at best, approximations) but you can easily detect no nitrite or ammonia when you test the water at a certain time of the day, but at another time of the day the nitrite and ammonia are well above zero. Try testing every half-hour for 2-3 hours after giving the fish a good feed and see what happens. But I do believe this fish is suffering from some sort of bacteria-mediated Finrot, perhaps caused by stress, including water quality problems. If one fish has ragged fins, then aggression of nipping may be an issue. But if multiple fish have ragged fins, then you have to suspect the environment as well.> I also turned the heat up a bit this morning because I keep reading that 80 degrees is best, and on my stick on thermometer (which I will be replacing because it doesn't give me a specific reading) was hovering between 76-79 degrees. So what now?  I'm wondering if I should treat him for fin rot. <Yes, but do bear in mind some medications (copper, formalin especially) can be toxic to catfish. Antibiotics should be safe though.> I am terribly upset that I took 4 healthy Angelfish from the store where they breed them, and have caused 3 of their early demise!  Am I on the right track? <No. You're doing a great deal wrong. Neither catfish species belongs here, and it's not entirely out of the question they're attacking the Angelfish at night -- after all, both species are predators, and while the Pimelodus pictus can be combined with Angels of similar size, they may go for small/weak specimens. The Ariid catfish simply don't belong at all, and though they are total pussycats when kept with brackish/marine fish of appropriate size (Monos, Scats or large Damselfish for example) large specimens view much smaller fish as food.> Also the sharks and cats are aggressive eaters but the Angelfish holds his own. <For now. Angelfish aren't adapted to fight for food.> I am feeding a combination of dried ocean plankton and flake food, is this sufficient? <Let's assume you're getting rid of the two catfish species -- neither species has any long-term future in this tank, so this isn't even something to delay or argue about. It's a done deal. You made a CAT-a-strophic mistake if you'll pardon the pun. A "tall" 20 gallon tank is adequate for a mated pair of Angels. Since you can't sex Angels, you can't buy a pair, so you need to buy six, rear them together, then remove the surplus fish. Realistically, you need 40-55 gallons for a group of six Angels up to the size when they'll pair off (around 8 cm/3 inches). So, what we're talking about is a single Angelfish here, perhaps with a 5-6 Corydoras sterbai (a good warm water-tolerant Corydoras) at the bottom and 6-8 medium-sized tetras (such as X-Ray Tetras, a very reliable, easy species) in the middle. All these would thrive on a mix of good quality flake and small sinking pellets (mostly at night, for the catfish). Augment with freeze-dried food if you want, but occasional live daphnia and/or brine shrimp are really useful for avoiding constipation.> Once this problem is solved I would like to get another Angelfish so I at least have a pair, is it wise to do so? <Keeping a pair is fine. Getting a pair is hard work. Two random Angels will likely fight, the weaker one being bullied. Has been tried many, many times. Unless you happen to get two females or a male/female duo that happen to pair off, this isn't a reliable approach. If it's any consolation, Angels can't always sex themselves either, and "homosexual" pairs are quite commonly reported, usually two females, each laying eggs on a leaf assuming the other was a male!> Thank you for your input! Darci <Hope this helps, Neale.> Sent from my Verizon Wireless 4GLTE smartphone <Oh gosh, another of these ridiculous "from my phone" messages… when will they stop? Who cares? Who's bright idea was this nonsense?>

Re: Ragged Angelfish Fins (also Ariids, Pimelodids in a very wrong environment)     8/19/12 I confirmed that the suggested fish were in fact what I have in my tank. <I see.> They will be going back tomorrow. <Wise.> I'm hoping the out of town store will take them in since the local store didn't care enough about them to give me complete and accurate information. <"Caveat emptor" I'm afraid. Welcome to capitalism. It's up to the buyer to make sure the thing on sale is what he/she needs -- the seller is under no obligation to sell you what you need!> I will then treat the Angelfish for fin rot and follow through with the other things you mentioned. <Good.> I have read I need to remove the carbon filter before I treat with medication, is it okay to replace it with  the filter floss during or before treatment or should I just remove the carbon filter insert and leave it empty until I am done medicating the tank? <I would remove the carbon and replace with filter floss.> How often and how much of a water change is needed during treatment? <Usually, none during treatment, but a good-sized (25-50%) water change a day after the last dosage is a good idea. Check with the instruction leaflet that comes with the medication you use.> How long after treatment should I consider purchasing the other fish? <As a rule of thumb, wait at least a month after any sickness before buying any new fish. That gives you chance to [a] make sure the sick fish is better and not contagious; and [b] to make sure the filter has recovered from any troubles that might have caused the fish sickness in the first place.> Thank you for your time and expertise! <Welcome.> Darci <Cheers, Neale.> Re: Ragged Angelfish Fins (also Ariids, Pimelodids in a very wrong environment)(Bob, does Melafix actually harm filters?)<<can>>     8/21/12 Good morning from Michigan! <Salve,> All the catfish have been rehomed. <Wise.> I picked up a bottle of Melafix to use for treatment. <Hmm… have you kept the receipt? This isn't a very reliable medication. At best (and I'm being generous) it has a mild antiseptic quality, so it's rather like dabbing a cut with antiseptic lotion. But it isn't an antibiotic, and once the bacterial infection is established (i.e., your fish are showing symptoms of Finrot) it isn't terribly effective.> I'm curious though about the carbon filter insert. <Junk it. Provides little value in freshwater systems.> Carbon is supposed to be changed every few weeks from what I read, so I wondered if its even active now. <Good analysis. The reality is that carbon works for around 2-4 weeks from new, and after that point it becomes so clogged with bacteria and detritus it's basically a biological medium. While it might be useful in that capacity, there are better media, such as high-quality ceramic noodles. There's some debate about whether "old" carbon can release toxins, but it can certainly mess up dosing medications, removing at least some of each dosage, so overall effect of the medicine isn't as expected.> I haven't changed it out for 3 months. I am curious though, if I remove the foam insert that has the carbon inside it, won't I also be removing the good bacteria that is keeping my tank chemistry stable? <Bacteria don't really affect water chemistry; their job is water quality, which is a much different thing. Anyway, you can remove up to 50% of the live media in a mature filter and have no impact on its working efficiency. Add some new media, and within days that new media will be fully matured. It's remarkable really, and an example of why bacteria are so useful in those applications where we've learned to "tame" them.> Since the tank stabilized I haven't changed this insert out of this fear.  Will the Melafix harm my biological system? <Doesn't normally, but it's a scattergun antiseptic, so there's always the potential.><<Can indeed destroy biological filtration. RMF>> Also I've considered adding live plants to the tank to enhance the biological filtration, what plants would you suggest? <The easiest plants are floating plants, especially Floating Indian Fern (sometimes called Water Sprite, Ceratopteris thalictroides). This plant grows in most situations, doesn't mind being under an aquarium hood (some other floating plants do), and its long roots bring plenty of helpful bacteria! It also happens to be hands-down the plant most loved by aquarium fish. You only need a bit -- it grows fast!> Thank you again for taking the time to indulge all of us novice fish keepers! <Welcome.> Darci <Do read: http://www.wetwebmedia.com/fwsubwebindex/phonyfwmeds.htm http://www.wetwebmedia.com/plantedtkssubwebindex/ceratopteris.htm Cheers, Neale.> Re: Ragged Angelfish Fins (also Ariids, Pimelodids in a very wrong environment)     8/21/12 I think I may have just had an epiphany, should I cut the bottom of the insert and just remove the carbon and leave the insert in place???? Darci <If that works, sure! Cheers, Neale.>

Columbian Cat Shark, comp., sys.   6/3/08 I have bought three Columbian Cat Sharks from my LFS. They were about 3 inches (2 weeks ago). I have put them in my 65 gal Reef Aquarium. Tanks mates are 2 common clowns and a six lined Wrasse which I think are going to be on the menu in a few months, but I have another marine aquarium they can be moved to. <Interesting set up. The Shedd Aquarium in Chicago used to keep some species of Sea Catfish (I think Ariopsis felis) in a tank that was essentially a giant reef tank in the Rotunda. Sea Catfish look *a lot* like small sharks, and it was quite something to watch them cruise that tank.> So far they seem fine with the soft corals and clean up crew, but when they get larger which is apparently going to be sooner rather than later given their current growth rate are they likely to eat the clean up crew as well, hermit crabs, turbo snails, emerald crab and common urchin? <More than just "likely", it's probable! These catfish are completely opportunistic predators, and a significant amount of their diet consists of crustaceans of various times.> The tank is furnished with macro algae, live rock, bubble tip anemone, devil finger coral, mushrooms, xiena and yellow star polyps (sorry about spelling?) These fish will be the priority in the tank and I wanted to create a aquarium matching there natural habitat so what should I used to create the biotype? <Sea Catfish are estuary/inshore water animals. You find them in harbours, around rocky reefs (oysters beds for example), mangroves, sandy estuaries, and so on. So while they're not really picky animals, they have a preference for shallow water habitats where they stick close to the substrate. Their whiskers, electric sense, and (apparently) echolocation sense all help them to find food in turbid waters where other predatory fish would be at a disadvantage. In other words: classic catfish habitat! A perfect tank for them would have some big rocks (with sessile invertebrates if you wanted) and caves, an open sandy area, and a HECK of a strong water current. Not too much light if possible; or at least concentrate the light on the parts of the tank where the corals are, and leave some part of the tank shady. That said, they're wonderfully adaptable fish, and provided they have swimming space and a few friends of their own species, they aren't demanding. They mix well with most marine fish, though I've found they don't get along with Triggerfish -- triggers use clicking sounds as threats, so misunderstand the clicking noises Sea Catfish employ when communicating. The triggers attack the cats, the cats start clicking because they're frightened, and the trigger gets even more irate. As you can imagine, this isn't what you want, because both species are well armed and able to dish out serious damage. Triggers have whopping great bite, while Sea Catfish have an anti-coagulant bite (causes serious bleeding) plus venomous spines.> Thanks <You're welcome, Neale.>

Survival chances. Ariids and Balas? -- 06/15/07 Hello! <Hail and well met.> I'm writing in regards to my 2 Colombian Sharks (about 2 inches long, maybe less). Well, the two that are left. (One died this morning.) I've done a lot of research lately and feel that these little guys are doomed. <I hope not! Among my very favourite fishes. A bit worried about doing research on fish *after* buying them, but I'll let that pass for now.> Currently, they live in a 55 gallon tank with 2 Bala shark. <Wronger than a wrong thing on the wrongest day of the year. Bala sharks are freshwater fish, Colombian sharks brackish water fish. These two species cannot be kept together for any length of time.> We're using the filter pump that came with aquarium. (It's a PetSmart aquarium kit). I don't think the filter is enough. <Possible. A ball-park figure for fishes this size would be 5-6 times the volume of the tank in turnover per hour. Perhaps a bit more if you can, because Colombian Sharks especially love strong water current. In static water they tend to end up treading water close to the filter pump.> We plan to add a under gravel filter. <UG filters can be an excellent choice in brackish water tanks. Set one up as per a marine aquarium, with a filter plate, crushed coral, gravel tidy, and then coral sand on top. Use two powerheads, one at each end of the tank. This'll generate lots of water movement as well as keeping the pH high and the hardness level appropriate to the fish. On the downside, the Bala sharks will hate such water conditions, but they're going to hate the salt even more...> After reading your FAQs, I learned that they are saltwater fish. <Not really saltwater fish. Hexanematichthys seemanni is a true estuary dweller, and adults as well as juveniles swim up and down estuaries far into freshwater but rarely any distance out to see. So while they do very well in saltwater tanks, they certainly don't need saltwater conditions. 50% seawater, or SG 1.010 is fine. High pH and hardness, and especially lots of water current, seem to be more critical.> I thought they were just brackish water fish. <They are.> I'm glad to know this because my husband disliked the idea of doing just a brackish water tank for these guys. Although, he really likes these fish. <As does everyone who keeps them. They look like sharks, but don't get too big (30 cm is typical), and are as gentle as kittens (except to anything they can eat, of course).> Here's my issue. I believe that I can not get anything bigger then a 55 gallon tank for them any time soon. <That's fine for now. Growth is fairly rapid for the first year, when they'll get to about 20 cm, but after that, growth slows down quite a bit. But long term, yes, you may have a problem. Realistically though, rehoming these fish shouldn't be hard. Big adults are always in demand for additions to jumbo brackish tanks or fish-only marine aquaria.> I live in a trailer home. I just don't think the floor with support a 100 gallon tank. It might support another 55 gallon tank at the other end. It may be half a year before I can afford another 55 gallon tank. Do these guys stand a chance of surviving that long with two Balas in a freshwater tank? <Difficult to say. Their tolerance of freshwater is very high, and specimens 10 cm plus can survive in it quite well, assuming the pH and hardness are high. I've even seen fully grown adults in freshwater tanks. They weren't happy, but they were alive. I wouldn't recommend keeping them in freshwater though. For one thing, you'll find they become increasingly neurotic, seemingly looking for a way out so they can swim "downstream" to the estuary.> If I do manage to get them into another 55 gallon tank and make it brackish water, how long do you think I can keep them in such living conditions? <Forever. They do fine in seawater, but do just as well in very hard, pH 8.0 brackish water at SG 1.010.> I plan to purchase a real house (eventually) and do a saltwater tank. This may take a few years and I have no idea if these guys will survive until then. If they do, will they get along with blue tangs and clown fish? (These are the kind of saltwater fish I /think/ I want) <I've kept Colombian Sharks in saltwater tanks with things like Panther groupers and Domino damselfish without problems. Anything too big to be swallowed whole will be ignored by them. Pufferfish work very well. The only problems I had were with Triggerfish, which hated the clicking sound these catfish make (the trigger attacked the cats, the cats clicked in distress, and trigger attacked even more aggressively).> What size tank would you recommend for a beginner in saltwater tanks? I know the bigger the better. I suspect that even 100 gallon tank might not be larger enough to start out with. I might as well find out now and start saving my pennies. <Indeed, the bigger the better. I guess it depends what you want to do. For fish-only aquaria, a 55-100 gallon tank is a great idea because you can keep a nice selection of the large but colourful animals that wouldn't work in a reef tank, like Triggers, Puffers, Lionfish, Morays, etc. Definitely worth sitting down with a good book and having a read. Bob Fenner's "Conscientious Aquarist" is excellent, and I say that without him looking over my shoulder telling me too!><<Hey! I see this here/now! RMF>> Thanks in advance for you advice. <No probs.> P.S. I would consider talking my husband into returning these fish to PetSmart, but they have new rules. They have decided that you should not have more then one shark in a tank. If you do, they will not accept returns. <Ah, a beautiful example of a Stupid Rule. For one thing, they're treating all fish with the word "shark" in its common name as being somehow similar. The problem with common names, and why experienced aquarists tend to dump them in favour of Latin names. What they mean to say is that people should only have one Labeo spp. or Epalzeorhynchus spp. "shark" (such as Rainbow and Red-tail Sharks) to each tank. That is indeed correct. But the Colombian Shark is not at all closely related to those fishes, and absolutely must be kept in a group. The bigger the group in fact, the better.> We were told by a fish store that Bala Shark, Colombian Sharks and Rainbow sharks would do well together. <Rainbow sharks definitely are aggressive and territorial. Bala Sharks and Rainbow sharks both need freshwater, Colombian Sharks brackish, so not really a viable combo.> Now, my rainbow shark lives in a 10 gallon by himself for sending a Bala Shark into shock. (Which ended in death.) <Oh dear.> The Bala and Colombian sharks get along fairly well and even try to school with each other. <How sweet! Both species need pals. Colombian sharks are rather adorable in this regard, and adults and juveniles school quite happily. People are sometimes worried about adding new catfish to the group, but no, they seem to really enjoy the company.> I suspect the employees are the fish store are pretty knowledgeable, they just refuse to tell us the whole truth unless we ask the right questions. <Perhaps. I can see where the Pet store is coming from, but in this case they've extended a serviceable idea way beyond its boundaries. Cheers, Neale.>

Arius seemanni Tankmates?  2/14/07 Hello, <Hi Glenn, Pufferpunk here> I have seemingly happy (8 cm) Arius Seemanni living in a 120 US gallon tank with (right now) a 16,5 PPT. <HUH?> My questions: Is there room enough for more fish? <Your catfish is a schooling species, so more of the same, would be my 1st choice.  A beautiful sight--a school of these fish!> If so what about 3 or 4 Mono fish? <Monos grow to a foot & would require around 300g for a school of them.> If so Mono fish, which one would be the best in my situation Sebae or Argenteus? <Neither, IMO.  Monos not only get large (as does your fish) but they are extremely skittish & your cat is quite the swimmer--not exactly a calming effect for a mono.> If not Mono fish, do you have any suggestions (knowing that I want to go light marine). <I'd say get a couple more Arius seemanni.> What about Damselfish in light marine in company with 2 Arius Seemanni? <You catfish will eventually eat them & anything else they can fit into their large mouth.  ~PP> Thanks, Glenn

Salinity Woes 11/27/06 I recently bought 1 Pleco (3 inch), 3 Cory Cats (1inch), an Iridescent Shark (2 inch), and a Colombian Shark (2 inch) for my 55 gal. aquarium.  I know that the sharks will outgrow this tank.  <Yep>  My question deals with the salinity of the water, as I found out (after the fact) that the Colombian Shark will prefer a brackish/marine environment as it matures.  How much salinity will my other fish tolerate?  Thanks! Kevin R. <Not much/any for the Corys and Pleco.  This mix is not viable for the long term.> <Chris>

Columbian Shark  Question  - 4/11/2006 Hi there! <Greetings> I have spent hours and hours (well. if I put all the hours together, they would probably add up to months!!) reading your fantastic site. And in preparation for my new marine project, I am currently reading your (Robert Fenner's) amazing book "The Conscientious Marine Aquarist". It's a fascinating book that has taught me a huge amount already and keeps me up reading into the late hours of the night :-) I highly recommend it.   <Me too> I was wondering if I could ask a question regarding my current situation. First, I will explain how I got there!! <Okay> I decided to add another tank to my collection - this time a brackish one since I love the Figure Eight Puffer. Once my 20 gallon was cycled and brackish-ized (!), <Heee! New term> I went to the local aquarium shop to purchase my Figure Eight Puffer. They recommended that I add to the tank two Columbian Sharks (Hexanematichthys seemanni) I was surprised as I thought Figure Eights needed 20 gallons each, <They do... and these catfishes much more> but they convinced me that the sharks would be a wonderful addition. And so off I went with my three new brackish friends . well, friends to me, not to each other. Needless to say my research was correct - I soon had to remove the two poor sharks when I woke up one morning to find they had both lost most of their fins - but I am relieved to say that after being placed in another tank and with much loving care and anguish on my part the fins are finally growing back. <Are very tough animals in good settings> Now, before I went to the store I hadn't heard of Columbian Sharks and just trusted the store's claim to "expertise" at the time. Since then, I have researched them and realize that as adults they need marine water and a much larger tank. <Yes> Since I am moving in a couple of months, I will be buying them a new tank when I move to my new place. So, now to my questions! 1. I know that the sharks need to be gradually acclimatized to a marine setup when they are adults - but how can I tell when they are adults? Is it according to size, months, years? <Size of the fish mostly... more salty with growth...> 2. And how gradually should they be acclimatized once they reach the age when their s.g. should be increased? <A thousandth or two per week of spg change is about right> 3. I wish my sharks to live a long, happy and healthy life and therefore before I invest in their new tank, I wonder if you could advise me on size. I was thinking of getting a 72" long tank. Is that a good size for them? <Yes> 4. Keeping in mind the sharks' adult size, health, happiness and bio-load, would it be possible to add any other marine fish to the new tank? <Yes> Or should they be kept on their own? <Are fine mixed with other compatible livestock... and nice to have motion, life in the middle and upper reaches of the tank> My favourite other fish are the Porcupine Puffer or a Trigger Fish. However, I know that both of those are aggressive species. But since the sharks will grow quite large, I was wondering if this will keep the Porcupine or Trigger away from the sharks and thus make them compatible. But if not, then I will not take the risk. <Easier going, starting small specimens, species of these would likely go fine> Many thanks for all your hard work in answering everyone's questions. You provide us with a very much needed support system and with an unending supply of knowledge. <Thank you for sharing, your upbeat note. Bob Fenner> Best wishes to you all, Sandra P.S. My Figure Eight seems very happy on his own. He has even trained me to understand what he wishes to eat. When he swims to the front of the tank and catches my eye, he will then look up when he wants shrimp but will hold eye contact with me while swimming downwards when he wants a snail. I learnt this the hard way - when he started doing this and I gave him the wrong food, he refused to eat but now that I understand his "language" I get it right every time and he eats his dinner to the very last bite!!

Silver tipped "Shark" Ok we were misinformed when we bought two "sharks". We were told they were freshwater and would be just fine in our tank with goldfish, spotted catfish and various "sucker" fish. We are very immature fish folk. Will these poor "sharks" die in freshwater? And if they need the salt, then we should get a separate tank most likely, yes? <Mmm, what you have are very likely minnow-sharks... cyprinid fishes that look "shark-like"... they are freshwater, not marine... and some are cold/cool water species, that can/do get along with goldfish (which are cool/coldwater minnows/cyprinids... Take a look on WWM here: http://wetwebmedia.com/FWSubWebIndex/minnowshks.htm.  Do you see your shark? If not use the search tools on Fishbase.org and Google... with the terms "silver shark aquarium"... and see if you can find the scientific name for your fish and go back to Fishbase.org and plug in this name. This will get you information on the habitat of this species. Bob Fenner><<Turned out to be an Ariid Catfish... please see the root/Marine web re. RMF>>

Arius Seemanni Compatibility <Hello! Ryan with you> Hi Guys. Your site is awesome. <Thanks!> I have a compatibility question. I have been told by a guy at a local tropical fish retailer that I could put a couple of Five-fin sharks (or Columbia Sharks what ever you would choose to call them these days) along with African Cichlids. I have been told and found sites to back this up, that the sharks would be able to protect themselves and do better in pairs than on there own. Is it true that I could put the sharks in with the cichlids? I hope that it is because I think those sharks are very neat to watch. What is your opinion? <I've tried this.  In a 150, I used to keep 10 assorted Africans, a few pictus cats and a pair of Columbia Sharks, Arius Seemanni.  Everything initially was a success.  After a year or two, the pictus cats started getting tormented.  The Columbians were not far behind.  They did defend themselves quite well, but it was stressful enough that I removed them.  Africans are unpredictable- This may work fine for years, or may be WW3 the second you remove them from quarantine and introduce them.  Does the benefit outweigh the risk?  That's the question you'll have to answer.  Good luck! Ryan> Cheers. Mike

Ariid Cat/"Columbian Shark" compatibility questions Hi Bob (or other WWM crew member),     Currently I have two 4-5" Hexanematichthys seemanni In a 30gal long (36x13), But I will soon be getting them a 180gal All-Glass drilled tank that I will use to rise the salinity up to 1.025 (over 18 months) from 1.000. Anyway, I would like to know if they could be kept with a yellow tang and a clown fish+anemone and other inverts. Thank You -Joey <Should work out fine. These are really beautiful catfishes, especially when large, in mixed saltwater settings. Bob Fenner>

More Ariid Cat/"Columbian Shark" compatibility questions Hi Bob (or other WWM crew member),     I have yet more questions about what I can keep with my Hexanematichthys seemanni. I was reading on WWM that some fish look at cleaner shrimp as a $1.75 snack. Are Hexanematichthys seemanni one of these fish? <Too likely yes. Bob Fenner> Thank You -Joey

Columbian Shark Needs Friends  4/25/05 <Hi, Pufferpunk here> I have a question about my aquarium. It is 20 gallons now but will be upgraded as needed within a year. The only fish in the tank is one very friendly Columbian shark named Antonio. The poor guy wants a buddy; I'm sure by the way he follows my finger against the glass. The problem is if we get another Columbian we won't know who is who. Is there another catfish or shark species that will keep Antonio company while the tank slowly shifts to full saltwater? <since Antonio is actually a schooling species, he would be happiest with more of his same kind.>   Perhaps a mail order outfit is available for other brackish catsharks? If the only species available are Columbian sharks, would a molly, orange Chromides or similar mid-water community type fish keep our little Columbian boy company? That is until Antonio eats this smaller fish! Thank you. <I'm glad you are planning on an upgrade in tank size & marine conditions.  A school of 18" silver sharks can be quite an impressive sight on their own!  Just make sure the tank is big enough.  ~PP>

Killer Catfish? Thank you! You really put my mind at ease. I love my 3 aquariums even if they got a little neglected when I had a baby last August (never to the point of bad water or disrepair, just not as diligent as I had been). Now that I am turning my attention fully back to my aquatic pets, I have one more question and I'll leave you alone. I have done a lot of research on this, but haven't come to a conclusion. I have an unplanted 55 gallon tank with two 330 Penguin BioWheel filters with a 4.5 year old silver tip shark catfish (Mack the Knife) and a large Pleco (Rainbow Barrone, Jr.). He had been coexisting with one Oscar who succumbed to old age. My husband was pretty heartbroken by Salvador the Oscar dying, so he didn't want another one. I got a Jack Dempsey, but Mack apparently killed him one night in a territory dispute. Short story long, is there any other species that would be compatible with Mack, or should I just leave him and Rainbow in there alone? < If Mack is going to kill all the new fish then I think leaving him alone is the best way to go>  Also, I've noticed Rainbow sucking on Mack lately. Is this a harmful practice? Should I separate them? Mack doesn't seem to mind as he just lays there. Thanks again! < Plecos have mouth parts for scrapping algae of things like rocks and wood. They will also scrape the protective slime off fish and can be a problem for fish like discus and angels. Little Cory cats on the other hand are just looking for bits of left over food and are harmless.-Chuck>

New Tank Stocking Hi I need a little information, if you don't mind. <It would be my pleasure.> I have a 10 gall tank, with 2 Arius seemanni, when I bought them they called them high bull fin sharks. <Call them what you want, these fellas are monsters.  Check out Fishbase.org, search for Tete sea catfish for more information on these fish.  I'd take them back to the store and slap the guy who sold them to you to put in a 10 gallon tank.  They will grow to be around 13 inches.> I have tropical fish pellets, 2 red tetras, and a bottom feeder.  I am confused on what to do for these fish.  I am reading that they are really salt water fish and they eat live food and will eat others in the tank. <If your tetras start disappearing, you will know why.> I also am not sure about what kind of tank I need, what about ph and what about mouth brooder what is all of this? <pH 6.0-8.0, brackish water would be best for long term health.  Mouth brooders rear their young in their mouth.> I am a beginner and in need of help.  I have had these fish for 3 hours and I am feeling as if I am way in over my head. <I would reconsider these catfish they are going to need a much larger tank, and brackish water.  There are some delightful tetras out there, maybe offer a trade at the store you purchased them from.  I love my black neon tetras.> Also I am wondering what could be wrong with one of these seemannis it has a swollen belly does that mean it is pregnant or has eggs?? <Probably not.  Missing any tetras?> Thank you so much if you take the time to answer these questions. <No problem, we have a ton of good reading out our site, I'd recommend starting at the link below.  Best Regards, Gage http://wetwebmedia.com/FWSubWebIndex/fwset-up.htm >

Big Catfish Hello, Tonight my hubby brought home two "silver sharks" for my tank as a surprise. After searching the web and much reading I've found that these are actually Columbian Sharks. <Uh oh> I am concerned as to whether or not these two new additions will get along well with the currant inhabitants in my 55: 3 clown loaches (2 1/2 inches) 3 yo-yo loaches (4 inches) 1 tiger barb (very young - 1/2 inch) 1 pink (kissing) Gourami (3 1/2 inches) 3 balloon mollies (1 adult female/2 juveniles) 2 Otos (young around 1 inch) ghost shrimp (roughly 15) I've read that Columbian Sharks can become aggressive and can eventually kill off my other fish. I really don't want things to come to this. So, would my current inhabitants be alright with these two "newcomers" or should I take them back to the LFS? Any suggestions or advice would be greatly appreciated. Many Thanks in Advance . . . ~ Vosklady <The Columbian shark is a catfish that can grow up to 13in, which is too big for a 55gal tank.  I would be willing to bet that as they grow they eat whichever tank mates can fit into their mouths.  They also prefer saltier water as they get older.  I would take them back to the store and go for at least 2 more Tiger Barbs, they prefer to hang out in groups.   Best Regards, Gage> Hi Gage . . . :) Thanks you so much for getting back to me, I truly appreciate it. I plan on taking the pair back to the store as soon as I have some time to do so sometime this week. Many Thanks Again & Best Regards, ~ Vosklady (Stacey)