meloyelo
Aquarium Advice Activist
About 3 weeks ago I had a major fish die off for no apparent reason. Out of 18 fish I lost everything except for my one peppered cory. Water consistently tests OK with 0 Ammonia, 0 Nitrites and only about 40 on Nitrates, so I assume it is cycled. I do 25% water changes 2 to 3 times per week since the tank is only a couple of months old. In the past two weeks I've slowly added back 3 platys and also 2 more peppered corys. Last night I added 3 more platys. This morning I look in the tank and 1 of the platys I put in 2 weeks ago is dead and another is having trouble staying upright. It then died about 1/2 hour later. That is the same thing that happened when I had the big die off. Fish would start swimming on there sides and then die. The other fish looked OK this morning and the corys have always seemed fine. They are always very active. Now here is were my question comes in. On the advice of the local Petsmart fish guy, I have never cleaned the gravel. He told me that it shouldn't be done due to lots of good bacteria being in there. I'm now wondering if my fish are basically swimming in a septic tank due to crud and such down in that gravel just rotting away and contaminating the water. I can't come up with anything else. I have noticed since putting all 6 of the new platys in that they stay up at the top of the water most of the time. The do swim around some, but mostly at the top. Suggestions?