Here is a problem I had with my 12 gallon AND my 24 gallon JBJ nano cubes, and how to fix it.
I have "lost" 3 fish IN the tank that jumped the partition into the filter part and landed in the back of the tank, and one was killed when it was sucked into the return pump. My threadfin (aka barberpole) shrimp goby was last seen half stuffed through the pump OUTFLOW tube in my 24 gallon. I had a six line wrasse stuck in a 12 gallon filter for nearly 3 months - I though he was just dead until he scared the heck out of me during cleaning. I have no idea what he was eating. I found fish parts of a firefish once in the filter sump, and there ain't no way in hell he fit through those slits. That's 3 that I know of, for a fact, to have jumped the partition and 3 different KINDS of fish to boot.
Go to the LFS and get a sponge filter pad for a sump. Something about 2 inches by 2 inches square and as long as needed to go accross the back of the sump part of the tank. Just squeeze it down in there a bit so that jumpers can't hop the wall and no problems. Now they bounce off the sponge and back into the main tank.
I have "lost" 3 fish IN the tank that jumped the partition into the filter part and landed in the back of the tank, and one was killed when it was sucked into the return pump. My threadfin (aka barberpole) shrimp goby was last seen half stuffed through the pump OUTFLOW tube in my 24 gallon. I had a six line wrasse stuck in a 12 gallon filter for nearly 3 months - I though he was just dead until he scared the heck out of me during cleaning. I have no idea what he was eating. I found fish parts of a firefish once in the filter sump, and there ain't no way in hell he fit through those slits. That's 3 that I know of, for a fact, to have jumped the partition and 3 different KINDS of fish to boot.
Go to the LFS and get a sponge filter pad for a sump. Something about 2 inches by 2 inches square and as long as needed to go accross the back of the sump part of the tank. Just squeeze it down in there a bit so that jumpers can't hop the wall and no problems. Now they bounce off the sponge and back into the main tank.
