Odd Harlequin rasbora behavior.

[Glenn407]

Have one rasbora out of about 9 or 10 that has been behaving strangely. It swims with the others as always but nearly always has his head inclined 30-40 degrees toward the top of the tank It can still swim with the best of them but at this tilted angle.. Still trys to join in the feeding frenzy but does not eat. There are zero other physical traits that are out of the ordinary on this fish or any of the others including about 15 various tetras. I don't have a ton of water parameters to give you at hand. All the rasboras are a year plus old, perhaps more. Nothing new had been added or done for months.

I'm hoping the lack of eating and the odd swimming angle will be enough info.

 

[Byron]

This could be one of several issues. I would just leave it alone, it may continue like this for some time, or it may not survive. Without a necropsy by a biologist diagnosing something like this is very difficult. Could be genetic, internal protozoan, water conditions (unlikely here, though tests for ammonia, nitrite and nitrate are advisable at any sign of "x", and the pH to see if it is normal), temperature shock...who knows. Many think "swim bladder" when they see swimming problems or buoyancy issues, but actual swim bladder trouble is almost never the actual issue, but a side effect of several other possibles.

 

[Glenn407]

Thanks Byron, I may just get the fish in a tank by itself just in case.

 

[Byron]

Thanks Byron, I may just get the fish in a tank by itself just in case.

Up to you, but I would never do this. First, it will cause severe stress to the fish which is already under stress. And chasing it around if that becomes necessary (and it is remarkable how agile a fish like this can be!!) will severely stress all the other fish. The injured fish will communicate via pheramones and these will be read by the others in the species, and this is not good for any of them.

The only time I ever worry about "disease" is when I see something that is obviously contagious and spreading. But if not, I let nature take its course. It is certainly kinder to all the fish.