Mystery Goby

[EvolutionOfDemise]

Not sure if this is the right section to put this in, but I saw a goby in a freshwater aquarium, labelled as 'Mystery Goby.' I'm interested in buying it but I don't want to get it and find out later that it's a brackish water species, so I thought I'd ask and see if any knows what kind it is.

Here are a few pictures;



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Thanks.

 

[nmonks]

It's a sleeper goby of some sort.

They're all pretty similar, though size varies. The average species gets to around 20-30 cm and is territorial, omnivorous (predatory, but will take some plant material), and essentially tough as old boots! Sleepers tend to be easy to maintain and quick to accept all sorts of foods beyond the usual river shrimps and earthworms; my Mogurnda eats Hikari Cichlid Gold without hesitation! Reasonably good community fish alongside peaceful tankmates too big to swallow.

Obviously yours is one of the bigger species. Mogurnda spp (all freshwater species) are pretty widely traded now, and Dormitator maculatus (a brackish water species) has been around for years. Recently some New Guinean species such as Eleotris margaritacea have been appearing in aquarium shops. This species is very similar to Ophieleotris aporos, a species from Southeast Asia. Eleotris margaritacea is essentially a freshwater to low-end brackish water species (though its larvae are marine fish) while Ophieleotris aporos is more a brackish water fish that is sometimes found in freshwater, so knowing which you have is important.

Look up those names and see if they help (your photos aren't good enough for me to identify the fish).

Cheers, Neale

 

[EvolutionOfDemise]

The names didn't really help, I looked them up, nothing. Maybe eleotris margaritacea? [font="Verdana][color="#222222"]I had put it on hold, and I couldn't really get a good picture of it. I can tell you it's about 6" long and dark blue with black markings.. And it's also pretty shy, but then again, it's also in an aquarium with a bunch of JDs.[/color][/font]

 

[EvolutionOfDemise]

I picked him up, he's in with my south americans, seems a bit stressed, bumping into walls. Fins are pretty damaged too.
Here's some better pictures;

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He should probably be in my quarantine tank, but it's being used.

 

[nmonks]

That's Dormitator maculatus, or something very close, a low-end brackish to marine species. It's quite peaceful, and shouldn't be with Central American cichlids. It does well with the usual brackish water livestock such as sailfin mollies.

Always the best approach with unknown gobies is to keep them in low-end brackish conditions. This won't harm freshwater species and will help brackish water species dramatically. The lack of colour on your specimen implies stress, so get this fish moved to brackish conditions ASAP. You should NEVER buy a goby assuming it's a freshwater species -- out of some 2000 species of goby, only 10% of them are true freshwater fish.

Cheers, Neale

 

[EvolutionOfDemise]

Thanks, from what I've read they're freshwater to low end brackish water. However, after doing some reading I'm pretty positive it's a marbled goby (Oxyeleotris marmorata) it's color is much bolder now. When I took those pictures I had just put it in the tank, so of course it would be stressed. Thus the loss of color.

It was already in freshwater when I got it. If it turned out to be brackish I was going to find a new home for it, but from what I've read marbled gobies are found mainly in freshwater. I may be wrong about the type, either way, both can be kept in freshwater. It's doing fine in my south american tank, I'll keep an eye on it for the next few days though.

And I believe brackish water could harm my catfish.

 

[nmonks]

Doesn't look anything like Oxyeleotris marmorata to me! For a start, Oxyeleotris marmorata is mottled brown, whereas this fish is brassy-coloured with obvious radiating stripes on the gill covers that i]Oxyeleotris marmorata[/i] lacks. Furthermore, Oxyeleotris marmorata has a longer lower jaw than upper jaw, whereas this fish has the opposite. I'm fairly sure this is a Dormitator species of some sort just because of its colour, dumpy-shape, and the way it swims in midwater (Oxyeleotris marmorata sits at the bottom by day, and prefers to burrow into the sand given the chance). Dormitator maculatus is particularly day-active and likes to swim about in midwater for long periods, something few other gobies do. Do also look at Dormitator latifrons, a similar species from the Pacific coast of the Americas as opposed to the Atlantic coast where Dormitator maculatus comes from.

Dormitator maculatus can survive in freshwater for long periods, but it really does need slightly brackish water to do well. At low-end salinity, SG 1.002-1.003 for example, that'd be well within the tolerances of most Central American cichlids as well as the common plec species (Pterygoplichthys spp.).

Cheers, Neale

Thanks, from what I've read they're freshwater to low end brackish water. However, after doing some reading I'm pretty positive it's a marbled goby (Oxyeleotris marmorata) it's color is much bolder now. When I took those pictures I had just put it in the tank, so of course it would be stressed. Thus the loss of color.

It was already in freshwater when I got it. If it turned out to be brackish I was going to find a new home for it, but from what I've read marbled gobies are found mainly in freshwater. I may be wrong about the type, either way, both can be kept in freshwater. It's doing fine in my south american tank, I'll keep an eye on it for the next few days though.

And I believe brackish water could harm my catfish.

 

[EvolutionOfDemise]

You're right, I made a mistake.
I've been planning on changing my gravel out for sand pretty soon here. Not sure about the low end brackish,. Here's a list of the fish I have in the aquarium;Tiger Oscar - Astronotus Ocellatus.

Green Severum - Heros Efaciatus

Gold Severum - Heros Efaciatus

Firemouth - Thorichthys Meeki.

Royal Pleco - Panaque Nigrolineatus.

Common Pleco - Hypostomus Plecostomus (6" growth was stunted by previous owner).

Delhezi Bichir - Polypterus Delhezi.

Senegal Bichir - Polypterus Senegalus.

Rope Fish - Erpetoicthys Calabaricus.

Fire Eel - Mastacembelus Erythrotaenia.

And I plan of getting a trio of Xenentodon Cancila.

I may just find a new home for it, we'll see what happens.

 

[nmonks]

Low-end brackish around the 1.002-1.003 will be tolerated by most Central American cichlids just fine. Several species actually live in brackish water in the wild. See my Brackish FAQ for details. The common plec species of the trade, Pterygoplichthys spp., will tolerate similar low-end brackish conditions too. I'd be surprised if you really do have Hypostomus plecostomus -- it hasn't been the standard plec of the UK or US trade at least for decades. Count the soft rays (not the single big spine) in the dorsal fin: 10 or more and it's Pterygoplichthys, 8 or fewer and it's Hypostomus. Finally, Fire Eels will be happy in low-end brackish conditions too.

Obviously you won't be keeping your Xenentodon cancila with all those cichlids or catfish, so they're not an issue. But they can, do tolerate slightly brackish conditions and are said to occur in seawater at times, but I'm skeptical. In any case, because Xenentodon cancila are essentially incompatible with everything else you have, you'd hopefully plan on keeping them in moderately hard, around neutral to slightly basic pH conditions. I cannot stress too strongly how bad it is to mix Xenentodon cancila with other species! They are extremely nervous and easily damaged, and once their snouts are snapped, they starve. A big, broad tank (at least 60 cm/2 ft front to back) is what they want, with NO TANKMATES.

Cheers, Neale

 

[EvolutionOfDemise]

From what I've read people have successfully kept xenentodon cancila with SA/CA cichlids providing the tank is large enough. I am planning to plant the tank around the sides since my fish don't really eat them. If they do I just regrow them in my other tank. The reason being is the plants would act as a cushion to avoid them from smacking into the aquarium glass. And I do have fairly hard water to begin with. I don't bother messing with it because there's no point. It always returns to what it was and the constant change is too stressful on my fish. If I were to get them it wouldn't be for a while, I still have a lot to do before I can. I'll look further into it. I'm not the kind of person that would just buy a bunch of fish, throw them into an aquarium and hope everything works out. With the exception of the goby, I usually plan everything out, keep lists and research. So I have read a lot about them, however I couldn't find much on tank mates other than a few forums and some websites. From what I did read I knew they are fairly peaceful and timid but can be kept with fish that aren't small enough to fit in their mouth and are not too aggressive. But like I said, I'll look further into it.