Murky Aquarium Water

Check your filer, Get some snails and/or bottom feeders.

On our recent visit to window shop at the pet store, we noticed that every single aquarium tank had thin slices of oranges in them and there was no odor.
I tried this on a single goldfish tank and it really helped the ODOR! Good luck. God bless you. : )

You did not say how large your Aquarium is, but the general rule is 1 gallon of water per a one inch fish, if you have a lot of sand or gravel in tank this will cause gas , do you see bubbles coming out of the sand or gravel? Your filter may not be strong enough , you could get another filter to add to the aquarium, but if over crowding is the problem , not much you can do, do you have extra air stones in it? I used to manage a pet dept, and this is the biggest problem, over crowding. For 5 medium fish , such as Zebras, mollies, guppies, ect, YOU NEED at least 1 gallon for each fish. also live plants help a lot too. Hope this helps. Rose

Generally the filter isn't working well. If you don't have "cleaner" fish/snails , after you've cleaned the filter and the gravel, get some cleaners.
Please don't use soap of any kind-- check with a aquarium store-- not a walmart store about how to clean your tank.m
good luck