Keyhole cichlid

[s0lange]

Hi everyone, I hope you can help me. We have a holding tank containing two keyhole cichlids which we have had for four months. We bought the fish at the same time hoping to have a pair. They were supposedly from the same spawning and were 3-4 months old when we brought them home. One was slightly smaller than the other and we think female.

The smaller fish has not grown at all since we have had her. The other fish is now roughly double her size and thriving. When you look at her, her eyes appear disproportianately large for her body, which is also rather too short for her body's depth. I am assuming for the moment that her growth may have been stunted before we purchased her. Her markings are very vivid - and always have been - consistent with a fish which isn't growing.

As long as she seemed happy so we were we however she has become increasingly shy as the other fish has gradually grown so much larger than her.

In the last week or two her feeding has become panicky. She darts at food overshooting it and then not noticing as it drifts past her only eating substantially when the corys in the tank get their sinking pellets every second day. In the last day or two she has begun to swim oddly, most of the time sitting on the bottom of the bare tank and propelling herself around the bottom. She doesn't seem to be able to float or control her swimming properly. She struggled to the top of the tank this morning at feeding time and it looked like a real effort. She lunged at food but again missed it before sinking to the bottom of the tank again and wriggling herself into a corner. I have no idea what's wrong with her. I suspect a swim bladder problem, but the sinking form is more unusual. I would appreciate any help.

Our holding tank is a 2ft 10gallon set up.

The tank is bare apart from plastic flower pots as hiding places.

PH is at 7.0

There are is no detectable ammonia or nitrite.

We do water changes twice a week

The water is treated with Seachem Prime and Acid buffer to maintain a PH of 7.0.

The cichlids are fed Sera cichlid pellets

In the same tank are 2 panda corys and 2 bronze corys.

They are fed on Sera sinking tabs and spirulina

Thanks in advance.