Brownish substance on walls of tank

Question
Theres a brownish substance all through our simese fighters tank he is blue his water seems to go cloudy quick and this brownish mould as i call it always comes back. Could you help me please?

Answer
Dear Tracey,
Brown algae is often a sign that the aquarium needs more frequent maintenance done. This is usually due to high nitrates in the water. *Cloudy water is usually due to a presence of too many nutrients in the water as well as there are bacteria and even sometimes infusoria that are clouding the water with their numbers and feeding upon the nutrient.

There's a simple solution to each of your problems. Increase your water changes please. Say if your betta is in a 1gal aquarium, i've had the best of luck doing 50% water changes twice a week (these are tanks with undergravel filters) and the water stays consistantly crystal clear. You should certainly have the same results.
(Always insure to make the replacement water equal in temperaure to that of your betta's tank and insure it is properly dechlorinated with a water conditioner every time)

I really hope this helps! Bettas are one of my favorite fish!!
Best wishes,
Karen~