My Fish Are Disappearing. How Is It Happening?

That is very odd! I don't know how big they are, but you might consider taping the lid shut if you have any pets around, and if you don't then I might think about the pump being the culprit. Silly I know, I had a suckerfish disappear too, and my cats never go near the tank. Never found it either. There could also be a chance that the catfish is eating the other fish, they eat them too, hope this helps, good luck.

The basic tank starts like this. One empty tank cleaned with vinegar then thoroughly rinsed, gravel thoroughly rinsed and added, water added, then put dechlorinator and good bacteria drops in water, then heater and proper bio filtration along with good lighting. To keep live plants alive you need at least a power compact light without that the plants will disintegrate and pollute the tank. Over feeding pollutes the tank the fish should be able to eat all food within a few seconds and be fed twice daily the rest of the time they will scavenge for food that dropped. Over population is common and the good rule of thumb is one inch of fish for every 2-3 gallons of water. So for example a goldfish that gets 12 inches will not survive in a one gallon bowl long before dying and would need at least a 36 gallon tank. When first starting a new tank a percentage of water needs to be changed at least 2-3 times a month until things balance out so testing water is a must. Some stones like limestone can make the water ph to high so be careful what you add to your tank. Some fish do not get along with others so it is important that the fish are all similarly sized and have the same temperament. Without more info this is all I can do. Here is a sight to help identify what fish you have and who they get along with...  www.wetwebmedia.com

Maybe one of the two left fish eaten the two fishes that had gone...

1. I do not have turtles.
2. The only other pet I have is a hamster, and he always stays in his cage in a completely different room. Also, I did consider the possibility of my catfish eating the other fish. It's just weird that he wouldn't eat a specific one.
Thank you for answering, though!

I had 6 fish when i was younger. I had no other pets either. One day i woke up in the morning and two of them were gone. I looked everywhere. The lid was on properly so it they couldnt really have got out. I took the pump out and looked inside it. There they were, dead though. Then i thought about that film, finding nemo. I felt sorr for my fish keeping them in thattank so i let them them all free in a lake :) hope that solves your mystery x

Do you have turttles? They could be eating the fish