red devil,,,that cannot float

Question
i have a red devil that is 5 yrs old,,,,all of a sudden she cannot float,,,she gets her way to the top of the tank to eat,,,but then sinks right back down??

also what can i feed these fish?

Answer
Hi Lisa,
From what you are telling me, your red devil is showing signs of Swim Bladder Disease.  SBD is caused by poor diet, and overfeeding.  Try to feed him cooked frozen peas with the outer layer removed.  Feed him nothing else for a day.  He must waste.  If he does not waste treat him with "Tetracycline" and follow the directions on the package.  Do not wait because this disease can lead to Dropsy which is very difficult to cure, if not impossible.
Red Devils grow to 15 inches, and need 60 gallons of water, and more is best.  This is very important to their health.  
He eats all kinds of flakes, fresh, and live food.  He should have high quality flakes, and pellets everyday.  As a treat you should feed him Brine Shrimp, frozen Bloodworms, plankton, and krill.   You may also feed him earth worms that you find at your bait store.  You must buy them at your bait store to be sure there are no pesticides in them.  To clean the worms, put them in oats for about a week.  Feed him earth worms only now, and then.  Never feed him feeder fish.  Feeder fish have no nutritional value, and are often full of disease.  You could also try to feed him regular minnows also found at your bait store.   Crickets found at your pet store may also be given.  Frozen fish that come from rivers, and lakes that you find at the market is also another food you may give him.  The fish must be frozen, and unfrozen before feeding your red devil.  Never buy fresh, always frozen.  He should also have veggies once a week.  These must also be bought frozen, and not canned.  Peas, green beans, broccoli, carrots, spinach, are all good for the Red Devil.  Cooked them first, and let cool before feeding these to your Red Devil.  Spinach, Zucchini, and leafy lettuce  are also good for him.  Cut the zucchini lenthwise.  A varied diet is very important to maintain good health.
Water changes every week is a must.  You must change 25% of his water weekly, and make sure there are no ammonia, no nitrites, and low nitrates in his water.  Check your water chemistry every week to make sure your water is clean.  Ammonia, and Nitrites are the main killers of fish.  You can buy these small test kits at your pet store, or Walmart, and they should be number one in your fish cabinet.
I hope this helps, and that your little pet will recover quickly.
Lynda