Last night I purchased 2 Red Tailed Sharks to add to my new 30-gallon freshwater aquarium. Upon first entering the tank, they were very playful with the Zebra Danios, Red Wags, and Sunburst Platys already there. However, this morning I found both of them nestled in the back right hand corner of the tank near the heater, alone and moving very little. I attempted to feed the fish bloodworms, flakes, and shrimp pellets, but they did not move.
Just now I returned from work and they're in the same spot and were disinterested in the food I placed in the tank.
The tank is about 3 weeks old and meets all the proper pH, ammonia, nitrate, and nitrite settings. The water temperature is currently 76 F.
Some of the Platys remain close by, near the heater, as well. Does the heater attract these type of fish? Should I be concerned with the sharks health?
I concerned because last week I purchased a Pictus Catfish from Petsmart, and after a week of anti-social behavior and little eating, the Catfish died. I don't want the same to happen to these two new fish.