Fish swimming near bottom...light problem or...?

[EVANOC]

Hi everyone...

We have a 20 gallon semi-aggressive tank with a collection of barbs, Buenos Aires fish, etc. In the three or so years that we've had it, our fish have never really been middle or top swimmers. Recently, as we've added more fish, we've noticed that they have all been gravitating toward the bottom, even moreso than before. We originally thought it might be a problem with the light. After a little experimentation of turning the light on and off, we found that they immediately move around once the light is off, and swim to the bottom once we turn it back on. We bought a new lower wattage bulb but it doesn't seem to help. Does anyone have any advice? Or an explanation for this phenomenon? It would, ideally, be a lot nicer for the fish to swim all around when the light is on...If anyone has any ideas, please let us know.

Thanks in advance,
The O'Connell Family

 

[Cian McLiam]

Barbs and Buenos Aires tetras are usually very active no matter what the lighting conditions, so Im not sure this is the problem. If it is, it will be difficult to dampen down the light, I would usually recommend floating plants or long stem plants like Vallis to cover the water surface. Unfortunately the Buenos Aires Tetras eat plants so I dont think this will be ideal.
Are the fish showing any other signs of distress?

Things to look out for include:

Clamped fins, holding fins close to the body.

Heavy breathing, one gill clamped or 'gulping' actions

Spots and lumps, especially white grainy spots.

Long stringy poo, not an ideal way to spend an afternoon, poop watching, but very helpful in diagnosing disease

Gasping at the water surface.

Scratching or 'flashing' off objects in the tank

Any of these signs could spell trouble for your fishies. Have you got a test kit for ammonia, nitrite, pH etc? If so what do they tell you?
Needless to say, when fish start acting strangely, thorough gravel cleaning and 10% water changes daily with water aged over night is a good first step.

Ken