Glassfish & Hatchetfish

[jtipton]

Both Indian Glassfish and Silver Hatchetfish are sold as freshwater in my LFS. I have read that they are both brackish. Is this true? What salinity is appropriate for these fish? What would be suitable tank mates?

 

[Colin_T]

Hatchetfish are freshwater only.
Glassfish can live in fresh or brackish.

Brackish water is simply water with some salt in. The salt level can be a small amount or almost the strength of seawater. Normally people run brackish water tanks at about half strength seawater.

Suitable tank mates for hatchetfish include tetras, small peaceful barbs and corydoras catfish.

Suitable tank mates for small species of glassfish include fish that tolerate the same water conditions (usually a slightly alkaline PH and a bit of salt) and are small and peaceful. There aren't really many small peaceful brackish water fishes but Pseudomugil signifer & cyanodorsalis (blue-eye rainbowfish), Chlamidogobius eremius (desert goby), and Etroplus maculatus (orange chromide) should be fine.
The bigger species of glassfish will be fine with bigger gobies, gudgeons and smaller peaceful perch.

Alternatively just keep them in freshwater with a slightly alkaline PH, a moderate hardness, and a tiny amount of salt. Then you can keep most other small peaceful freshwater species with them.

 

[nmonks]

I broadly agree with Colin's comments above, except to say that I've seen no evidence that glassfish need hard/alkaline water, and suspect this is a bit of myth. I keep my specimens in a 50% mix of rainwater and tap water such that the pH is around neutral and the water hardness around 10 degrees dH. I have also kept glassfish in soft/acid conditions and encountered no problems.

The Aqualog book on brackish water explicitly calls glassfish "brackish water fish that aren't". I think this sums it up quite nicely. They're collected from similar environments to barbs and gouramis and can be kept in equivalent conditions. Some species are found in blackwater streams, and others in river rapids hundreds of miles inland!

I have mixed glassfish with silver hatchetfish and they work together fine. In fact, the hatchets would try to school with the glassfish! Glassfish are not completely peaceful, and while they certainly should be kept in groups, what you will notice is they spend a lot of time "diving" one another, I suppose to assert their position in the social structure.

They're both nice fish, so good luck with them.

Cheers, Neale