black pests inside my fish tank.

Question
Hi I have a problem with my 20 long fish tank that i have had for at least  5 years. The filter i have is a tetra tech for a 30 gallon tank. Help! My problem and concern with this tank is that i have one bristle nose catfish living in this tank but it seems that there are these on going pesky annoying bugs that look like tiny black worms then turn into little flys. They fly out of the tank everytime i open the fish tank lid. I've changed the filters several times five done water changes five done this several times throughout the year and nothing. I'm wondering if the quality of the food has anything to do with it. I've lessened the food that ive given the fish ive reduced their feedings to once a day. I have the wardleys brand fish flakes. Also im thinking of changing my gravel to another color and what not. Its been a few years since i have changed it and was also wondering if this also has anything to do with problems in the water and or tank?  sadly this problem is also in my 10 gallon fish tank as well. Same problem. Any help that can get rid of these bugs will be much appreciated. Is there any fish tank bug traps i can put in the tank or a certain fish that will eat these pesky tiny gross black worm like things? Thankyou.

Answer
Hi Kerri,
  The problem is nothing to do with your gravel or anything like that.  Basically, a kind of fly is finding its way into your tank, laying eggs, these hatch into larvae which then metamorphose into flies.  Most flies will only lay eggs in still water.  Is the water at the top of your tank very still?   If it is, consider adding an airstone that agitates the surface more.  That should stop the problem.  Also, you should be changing 25% of the water in the tank once a week, every week to keep the water quality high.   You should only feed your fish once a day and only give them food which they eat right away.  Never give them food "to eat later".  It will rot and create
all sorts of problems.

-- Ron C.
  rcoleman@cichlidresearch.com
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