spots in my tank??

Question
hi my friend just got a 100 gallon tank from a friend and she bought 6 neon tetras and 3 guppies for it but then decided they looked too small in the tank and yesterday bought a large black goldfish and today asked me about some green/orange spots that have developed on the glass towards the top of the water she doesnt know what it is and i was just wondering if it is a hazerdouse algae or not and whats the best way to clean and prevent it

Answer
Hello,
Green and Brown spots sounds like algae. Alage isn't harmful it just doesn't look good. The best thing you can do is get an algae scrubbing pad and wipe it off. The best way to prevent it is to keep the aquarium light off as long as you can. Even if you only turn it on to feed them or view them. Hope this helps!