He's bee pretty slow moving yesterday and today. I gave him a 75% water change the other day and since then he's been acting strange. He came up and ate a little today but he's just really slow and not active. He doesn't look to be ill or anything. doesn't seem to be swimming abnormal besides slower and not much. Also he hasn't made a bubble nest since he got his new 5 gallon home about two months ago. Any ideas?