Bettas laying at the bottom of their tanks

[bparnold]

I put some other small fish in the tanks with my kids' Bettas-the other fish did fine and were quite active but the Bettas' activity levels have droppped-off to almost nil.

I took the other fish out but now the Bettas are laying on the bottom of their tanks! What gives-why are they doing that?!

[Chrisseh]

The ammonia could be high. I would do a water change. See if that helps

[dramaqueen]

Having the other fish in with them could have stressed them out.

[iamntbatman]

How big is the tank? How long has it been set up? How many other fish did you add, and what kinds of fish were they? If you put too much stress on your biological filtration, the ammonia could have spiked which would explain the lethargy. If you don't have a test kit to test for ammonia, just doing a water change as Chrisseh advised would probably be beneficial.

Do you have a heater? Bettas also become lethargic if their water isn't warm enough. They should be kept at 78-80 degrees.