floating at the top of the tank

Question
i have 3 goldfish in my tank which is a aqua qube 25 and can hold 25l of water. 1 of my goldfish is worring me as he just stays at the top of the tank and does not swim around apart from when he stuggles to swim to the bottom of the tank i think he has lost his buoyancy. i think he maybe dying. can someone please help me save him.

thnaks ian

Answer
That is only 6.6 US gallons, very small.  It is not large enough for one goldfish.  You should try to get a tank at least 5 times bigger.  Problems swimming are pretty common with fancy goldfish.  Which variety of goldfish do you have?  If it's fat-bodied, then the swim bladder is going to be such that the fish may have trouble swimming.  Swim bladder disease is basically this problem.  Sometimes, it can be improved by pre-soaking food before feeding it, feeding sinking foods instead of floating, or feeding cooked, peeled peas.  Often, a larger tank will help a lot.  Have you tested your pH, ammonia, and nitrite lately?  If they are off, a fish may also have trouble with buoyancy.  How often and how much water do you change?  I do 50% a week in all my tanks.  If a tank is overcrowded, you may need to do it even more often.  Good luck!

Robyn
fishpondinfo.com