Hi, I hope someone can help. I have a betta in a 20 gallon community tank. He has been doing well and getting along great with everyone until last week. For one day he was displaying aggression to only the 2 orange fish in the tank (displaying, chasing, nipping) Then he retreated into the rock cave we have in the center of the tank and has been there for 3 days. He doesn't come out and won't eat. This morning we did a partial water change and was able to get him out of the cave. He seems lethargic and, well, "Droopy". I checked all the levels in the tank- no ammonia, ph stable, temperature stable. All the other fish are doing great. Is this a mating cycle perhaps? Should I be worried? This betta is gorgeous- blue, pink and purple! I don't want to loose him!! Thanks for any help you can give me.