Hello I'm 3 mths into this so newbie fits me. Freshwater 16 gal tank, one female betta four spotted cories (love them all) three cories normal spotted. one named William Wallace named for the fly to the top and side to side making me think he's wants freedom... he's about 3/4 in and he's getting paler, he eats brine shrimp well swimming around the top to get at it. He swims stong up but he seems to go limp and float down. He seems to skim top, sides and foam filter most. He gettng paler, the others are all fine. Any suggestions or similar situations?