[Jirajustin]

Can anyone help me identify whether or not one of my Exclamation Point Rasboras is suffering from fin-rot, or if the fin is falling of due to another injury like damage?

About 2 months ago, I noticed that one of my Rasboras was of a slightly darker shade in colour than the rest of my fish. Apart from this it didn't look or behave any differently from the others in its school.

Later in the month I noticed that its dorsal fin was always extended, and would not contract and move like normal, and the base of the fin was reflective. So when the light hit him in the right way he would stand out because of this reflective patch.

About two weeks ago, I realised that his dorsal fin was detached from the rest of his body and was starting to fall over.

The fin as now fallen over completely, and rests beside his body as he swims. He eats fine, and keeps up with the other fish, but remains a slightly darker shade of brown in his body. The reflective patch appears to be the tissue below the fin where it has fallen off.

I couldn't get a very clear picture because they're so small, but to give you an idea of what this fish looks like I have a picture of a Boraras Maculatus from my tank, which is a related species.

If it is fin-rot, what should I do?

 

[WaterLife]

Fin rot would look like the fin is rotting away or getting gradually bitten/munched away (from outer edges disintegrating down to the base). So from the sounds of the dorsal fin being broken and it hanging by the fish's flank, it just sounds broken somehow (injury). Not completely sure if the whole dorsal fin can either repair itself upright or regrow a whole new one.

 

[Jirajustin]

Yeah! I thought it didn't really quite match the descriptions of fin-rot that I've read. I think it may be due to damage from a territorial gourami I've had in my tank with the fish recently. I'll keep watching him and see what happens. Really hoping its not at all infectious.

 

[WaterLife]

Doesn't match any infections I know. But a injured fish is in a weakened state and any open wounds are more vulnerable to infection so clean water is important to keep vulnerable fish from contracting "secondary" infections. As long as the injury doesn't appear to worsen or deteriorate further, it should be fine and not be an infection/disease.