Damselfish Identification - Neopomacentrus; & BR use         11/20/19
Good evening,
<Hi Joel>
I was at a local fish store today and came across these two lovely looking Damselfish in the store's batch of "Assorted Damsels". I've only been keeping saltwater fish for a short period of time, but have sufficient experience in brackish fishkeeping to tentatively identify them as Freshwater Demoiselles (Neopomacentrus taeniurus). I've never seen them before in person and pictures online of the related N. cyanomos sometimes appear similar, so I was hoping you might be able to verify for me.
<These appear to be Neopomacentrus taeniurus>
Sadly, I don't think they are appropriate for either of my tanks. My 125 gallon brackish tank at 1.006 may be too "fresh" and may squabble with the 8 Orange Chromides in it. On the other hand, I'd worry that it would fight with my Talbot's Damsel in my 55 gallon saltwater.
In either case, just seeing this rare (to me) Damsel was enough of a treat.
Thank you for your time.
Joel
<Am going to ask Neale Monks here to respond re Pomacentrids for brackish systems. His background w/ such systems is extensive. Bob Fenner>
Re: Damselfish Identification - Neopomacentrus /Neale        11/20/19
Hello Bob, Joel,
<Neale>
Yep, agree with the identification of your damselfish as Neopomacentrus taeniurus, but with the cautious that there are other species, such as Stegastes otophorus, that do look quite similar (especially the yellow tail). That said, Neopomacentrus taeniurus does have a more deeply-forked tail, suggesting your initial identification may well be correct.
I’ve seen Neopomacentrus taeniurus kept in freshwater tanks where they had been in situ for at least six months, seemingly without harm. Companions including Corydoras catfish and Angelfish of all things, and while the water was certainly hard, it wasn’t salted. I suspect 1.006 will probably be tolerated perfectly well, as these are truly euryhaline fish rather than marine fish that happen to handle brackish water for longer or shorter periods (as would be the case with, for example, Sergeant Majors). In some places (including various oceanic Pacific islands) they inhabit completely freshwater habitats alongside classic peripheral freshwater fish types like Gobies that, in common with Neopomacentrus, have a marine reproductive stage but as adults inhabit freshwater environments. I believe Neopomacentrus taeniurus breed in the sea, however, rather than spawning in freshwater and leaving their eggs to drift into the sea. Hence finding Neopomacentrus taeniurus in freshwater, brackish, and fully marine habitats.
<Ahh>
My understanding is that they’re often found in harbours, estuaries, and tidally-influenced rivers and streams, often quite murky ones (hence their drab colouration). Water depth is rarely very great (less than 3m by one source). Allen refers to them as dwellers of ‘inshore reefs’ so I guess your classic coastal rocky reefs with oysters and mangroves rather than offshore coral reefs seem to be their preferred habitat. My guess would be that they’re much like various Apogon and Gobiidae species that are found in such places: perfectly well adapted to varying salinity, able to handle low salinity, even freshwater, for extended periods, but probably happiest (in the sense of being able to spawn successfully) when kept in mid to high end brackish conditions or fully marine salinities.
They are planktivores by nature, but consume all the usual foods that you’d give small Damselfish.
I agree, Orange Chromides would likely be viewed as a competitor. There’s no particular reason you couldn’t accommodate both given sufficient hiding places, but you’d certainly want to plan ahead. I don’t know enough about Neopomacentrus generally to comment on their social behaviour towards other Damsels in a marine aquarium, but would imagine Neopomacentrus taeniurus are par for the genus. Possibly Bob can add more here.
<The genus is more toward the easygoing spectrum of damsel territoriality; not quite Chromis. I do consider, as you've stated re habitat, that they should co-exist w/ Chromides.>
That pretty much covers what I know! The problem is they’re hardly ever imported, and almost never kept in freshwater or brackish systems. I’m not aware of any long term records beyond what I’ve reported above!
I’d be tempted to try them out with the Orange Chromides, and as/when they mature, if they start looking seedy, or else behave abominably, then move them into a more rough and tumble FOWLR system.
Cheers, Neale
<Thank you, BobF>