Ok so, in my 30 gallon I've got 1 angelfish (about 2 1/2 inches tall), 6 zebra danios, 1 black neon, 1 sailfin pleco, 1 gold stripe cory.
This morning I wake up and I've only got 4 zebra danios.
The aquarium has a top and the only spots its open are where the heater goes and where the filter is...