What is this whiteish clear cotton like fungus that keeps growing in my fish tank?

Answer 1

Does it look something like this: http://www.visualsunlimited.com/images/watermarked/227/227311.jpg

This is either Saprolegnia or Achyla, two aquarium "fungi". I use the term loosely, because that's how you'll see it listed in aquarium references, but it's now reclassified.

It needs an organic substance to grow on, so there's probably uneaten fish food or fish feces on your gravel. It takes about 2 days to get the amount of growth shown growing on the dead bug in the photo. There's really no way to keep it out of your aquarium - all you can do is to not provide it places to grow. Use a gravel vacuum to siphon out the fish feces and any food not eaten after a few minutes.

Answer 2

Its probably algae. Most likely causes:
1) Your putting too much food in for your fish.
2) Your tank is in direct sunlight.
Buy a plecostomus. They graze the algae right off the glass.
Also, do regular water changes.
If you mean its growing ON your fish, buy some fish fungus treatment, take out some tank-water in a bowl, and mix the medication in. Put all your affected fish in for 10 minutes, then put them back in their tank-minus the treatment. Repeat this every day, along with water changes in their tank. Usually, fish get fungus through stress, so something in your setup is wrong. Check your biological filter.

Answer 3

i believe that is algaes. i can't say much for you didn't give much info.