Hi! I have a half moon betta in a 2.5 gallon filtered, heated tank (best I can do for the space). Sparkle has been thriving here since February. The tank is cycled.
Very suddenly, after cleaning the tank (details below if you want them), Sparkle isn't eating. A few days ago, I noticed he would take the food in his mouth and then spit it out and let it fall. So I cracked the pellets smaller (they aren't new, its all he's ever eaten) and same result. Today I bought some pellets that aren't really pellets, they are like shavings (API brand). Same result, he's spitting them back out again.
He swims around the tank and will greet me by opening his mouth several times at me, so I think he's hungry. But everything he eats comes right back out again.
Is he sick? Do bettas get mouth sores? Is it related to cleaning the tank? Do I just keep offering, hoping some of it gets into him? Anything else I can do?
Additional info: I cleaned the tank last Tuesday, ammonia was 0, nitrite was 0, and nitrates were 80 before I cleaned it. Sparkle was in a cup, I vacuumed the gravel and rinsed the fake plants and decoration, and replaced the carbon filter. I wound up replacing 60-70% of the water with conditioned water (Prime conditioner).