1 eyed zebra fish

Question
the tanks been set up for 2 months
tank size is a ten gallon
1 ghost knife,4 small goldfish , 3pink neons ,1 tetris and 2 zebra fish 10 all together
the filter type is a whisper 10
ph ammonia nitrite level is 7.2
we change the water 1 a month
10 gallons of water are replaced every time
i origanally had 3 zebra fish but got eaten last month because it was ill once he died we cleaned the tank.On friday my pink tetris fish died so now i have one tetris but we put 2 drop of the ammonia killer in.And the main wierd part is when i first got all three zebra fish i noticed 1 of them had a swollen pink eye odd enough its eye healed when i put it in the tank but that one is still alive now the other zebra fishs eye is missing is this because of agresson?

Answer
Hi Jessica;

Your tank is just far too small for those fish and you have some compatibility problems too. You need a much bigger tank for them... actually two more tanks; One warm water tropical and one cold water, each at least 40 gallons.

The goldfish and ghost knife are probably getting aggressive and frustrated with each other and the other fish. The ghost may be biting them all at night. He is predatory and nocturnal. He can eat the whole fish or pluck the eyes out. He can't help himself, it's just what they do. They hunt for food at night when the others can't defend themselves. The ghost knife will slowly eat all the small ones as he grows. He is aggressive, needs live food and will grow to be VERY large.

Goldfish are coldwater fish. They need a tank with no heater. They also grow too large for a ten gallon and will eat your tetras and zebras soon. Goldfish are very messy guys that need ten gallons just for one and grow to be over 6 inches long.

The only fish that should be in the ten gallon are the tetras (neons are tetras too) and the zebras.

Good luck...

At Your Service;
Chris Robbins