I have about 40 RETF tadpoles in a rearing tank at the moment. They are about 4 weeks old now. Seem pretty healthy. Growing, eating, swimming.

The past week, however, I've started getting deaths within the population. Not massive numbers. Maybe 1 a day if that. I think in total I've lost maybe 6-7 so far. But it's happening regularly it seems. Each day there is a new lifeless tad at the bottom of the tank. I quickly remove the decease from the general population. Some tads have been victims of cannabalism as when I find them they are missing their tails. Others are full tads.

Nothing has change aside from the fact that I add water to the tank to give them more space. I feed them daily, a mixture of tadpole pellets and tropical fish flakes. They don't have a problem eating. The water is distilled treated with blackwater extract, Java moss, indian almond leaves and duckweed. I have an external canister filter and water heater also. The heater and filter have been separated from the tads using a screen mesh.

Is this normal? At this rate I may not have any left once they are ready to transition out of the water.