Though amongst the least motile fish groups (though about the fastest in terms of gulping live prey!), and grotesquely roundish to globose (though often spectacularly marked and colored), Angler or Frogfishes are perennial attention getters in public aquariums around the world, and though rare, do make inroads to aquarium stores. As a group, Anglers are hardy, tolerant of a wide range of aquarium conditions… Some of their few outstanding faults as marine system captives are their penchant for inhaling fish tankmates, and already-mentioned inactivity.

Identification, Systematics:

Anglerfishes are members of the living Order Lophiiformes; an expansive assortment bizarre-shaped predaceous species that includes the non-aquarium but important food fishes called the Monk or Goosefishes (family Lophiidae). Of the other Lophiiform families, most folks are only familiar with the abyssal depth Anglers, family Ceratiidae… these and some other deepwater groups get a good deal of photographic exposure in the popular press often shown (greatly blown-up in size) as hideous monsters… with large mouths, sharp teeth and deep gullets. Most of these fishes are smaller than ones finger. The deepwater anglers are notorious for their "parasitic" males that attach to females in an obligate life-long association, becoming nothing more than attached gonads/gamete contributors.

The group includes a few suborders (five in the present, more popular scheme) and sixteen (to eighteen) families, about 65 genera and three hundred species... some are dominant forms in the abyssal depths, others lurk just under the substrate... all are cryptic and unseemly in appearance (at least to me...), though of course, "beautiful" in their own rights.　As aquarists we are concerned with the few continental shelf dwelling species that happen into the trade of the family Antennariidae.

A Gallery of Some Commonly Encountered Antennariids:

Frogfishes comprise some 41 species in 12 genera. All are interesting enough for consideration as aquarium specimens. Some are "shaggy" in appearance, others occur in a myriad of colors, patterns (and change both), but only a few are offered in the aquarium trade on an irregular basis. Worldwide in distribution, mainly found living on the bottom amongst sponges and rocky reefs, though one, the Sargassumfish, floats free amongst the kelp of its namesake.

Here we’ll list the most often available amongst the 41 species of the family. Do know that many "common" listings of retailers, even wholesalers prove inaccurate… that Anglerfishes are often difficult to determine as to species (diagnostic features like fin ray counts are hard to do… fish rods and baits get bitten off, back…)… and hence are often listed/labeled by "color" (which changes) or as regional "types". Species identifications rely on variable structural traits, mainly the "fishing apparatus (illicia, escae), shape and number of dorsal spines, fin ray counts, presence/absence of "warts", shape of caudal peduncle, and placement of the gill openings.

Behavior:

Mmmm, sedentary for the most part, Anglers can/do get up and about if disturbed, "walking", and even "galloping" on their stiff downward directed pectorals. They’re not lazy assuredly, but masking their appearance in order to seize unwary prey. Their collective nominative relates to the modified anterior dorsal fin ray… the "pole" of which (illicium) is capped by a variously shaped and wagged "lure" (esca). In an established setting, well-adjusted specimens will "fish" with this apparatus, hoping to lure in meals.

Yawning behavior is quite common, and is usually indicative of either over-stress, or aggressive display.

Compatibility:

　　　 A few species make their way into pet-fish markets... the most important element to keep in mind in their captive husbandry is their penchant for swallowing their tankmates. Some authors (Michael of note) endorse the keeping of more than one species, specimen of Angler together… with the proviso that they not be too disparate in size AND be well-fed to prevent predation/cannibalism. Indeed, Anglers can fit fishes of more than their own length into their distensible mouths and gullets. Better to be safe and only house one to a tank IMO, or with other smart/aware, fast-moving, but otherwise disposable fish species.

Selection:

Healthy Lophiiform fishes exhibit the characteristic of "brightness", in appearance and behavior. Their eyes should be clear, and aware; shifting to your movements and other stimuli. Unless recently fed to satiation, they respond positively to the presence of potential foods, stalking or "fishing" for them.

Newly arrived specimens should be left a few days or more to "rest up", maybe held on deposit, before taking them home for quarantine. Care should be exercised in moving these animals in slow, deliberate motions, NOT exposing them to the air where they make "suck in" the atmosphere, too-likely succumbing to trapped gas from such air induction. Instead, keep them always submerged, and yes, risk the introduction of possible pests, parasites through the processes of acclimation, quarantine and movement to their permanent display setting.

Systems:

Though inactive to the point of not moving much at all, these fishes can generate considerable nitrogenous waste as a function of their gluttonous appetites. More volume of course allows greater dilution of wastes, more stable gaseous exchange and water chemistry, and a wider margin of safety should "something" go wrong. If kept as an individual in a species tank, smaller species can be maintained in systems of a few tens of gallons. Larger ones require hundreds.

Décor is important. Anglerfishes rely on mimicry to find food and avoid predators, in this case blending into the reef itself. They are indeed such masters of disguise that most divers miss them entirely underwater, even when their very masks are pressed up against them! Not being venomous or poisonous, they count of not being detected to escape predators and lure living food items their way. For their psychological well-being, providing rockwork, maybe real or faux sponge material of a suitable colour (they can/do change to match). And this all being stated, do leave a good bit of open areas where they can "walk about".

Foods/Feeding/Nutrition:

Anglerfishes fresh from the wild (all are wild-caught) must have live foods regularly supplied or be trained to take fresh/dead foodstuffs from a wiggled feeding stick.　Some individuals will only ever accept live foods, though most can be trained on to wiggled whole, dead foods placed in front of them. Food prey is preferably of marine origin.

Disease:

Anglers are notably susceptible to Cryptocaryon and Amyloodinium, and are often infested with these single-celled protozoan complaints on arrival due to the stress of shipping and handling. Though hard to make out, sick fishes look "puffy", often with sunken, lightly opaque eyes and rapid breathing. They respond poorly to copper exposure, and so should be treated with quinine compounds (e.g. Chloroquine Phosphate), and possibly hyposalinity (lowered spg.) protocol.

Another too-common source of mortality of these fishes is directly due to over-feeding habits of aquarists. Specimens that eat too much or too large food items may face a situation in which the meaty item/s decompose faster than they digest, resulting in them becoming gas-filled and floating at the top of the tank. Either the fish will expel the air or succumb. The lesson here: Feed sparingly and not too often… with offerings no more than half the length of your Angler. Oh, and it should be restated that similar gas-entrapment can/does easily occur if these animals are lifted into the air; therefore capture, bag, introduce them underwater.

Collateral damage from collection, handling and especially bag-rubbing in transit can be severe, and thankfully Antennariids are rapid and ready healers. Should yours appear bad off in terms of secondary (bacterial et al.) infection, remarkable results have been had in treating with the controlled antibiotic Chloramphenicol Succinate (at a rate of 1 gm./200 liters (52 actual gallons)). This compound may be obtained through your veterinarian.

Reproduction:

Of species I’ve observed and read records of, Anglers have a sped-up courting process in which smaller males nudge and pursue larger egg-laden females. Eggs are laid at night in sticky scroll-like batches and fertilized by the pair as they adjoin each other. After a period of time, this floating, gelatinous mass settles to the bottom. Some Frogfish species exercise a modicum of parental care, guarding the fertilized eggs. In all cases, the eggs hatch and the young are planktonic, spending one to two months floating in the upper water column.

If you should have two (or more) specimens of the same species together that don’t each other… and end up spawning, it’s strongly advised that you move either the adults or egg raft and earnestly seek out or try culturing suitably small (less than newly hatched brine shrimp) foods for the young.

Cloze:

The aquarium Angler or Frogfishes are known just as well for being odd-appearing as for their fish-inhaling capacities. Called Anglers for their specialized "fishing apparatus" and luring behavior for drawing unsuspecting fishes near, and Frogfishes for their squatty appearance and pectoral-fin hopping motility, these species can make for hardy, though cryptic aquarium specimens. In most settings, this calls for a dedicated "species set-up" or use of sessile invertebrate and sturdy-aware otherwise tankmates.

Not the most dynamic of fish families to house, Anglers are fascinating and can be quite long lived, given attention to careful (under) feeding, water quality and care not to have them sucked up against intakes…

Though certainly not for everyone or any given system, the Anglerfishes are indeed unique and (to some) beautiful animals. Their eye-blinking feeding speed, first accounted by none other than Aristotle in 344 B.C., is unmatched at some 6/1000 of a second (now that’s a rapid gulp). Accounting for their propensity for sucking up most all fishes and shrimp in their system and leaving out fishes that might harm them is about all that is otherwise required to enjoy their captive company.

Bibliography/Further Reading:

http://www.starfish.ch/frogfish/Anglerfish.html