Hey all, I did a 50% water change on my tank (i ONLY do these once a month) yesterday and rinsed off all the items in the tank because of the diatoms. I noticed my betta was acting a little odd yesterday, hanging out at the bottom fo the tank and he looked a little pale, i figured a water change and some bring shrimp would perk him up a bit. He ate a little bit (maybe 1 or 2 shrimp) and i figured he was OK so i went on about my day. I woke up this morning to a very ill fish. He is on the bottom of the tank breathing heavy and the inside of his gills seem red (i am not sure if this is normal for a betta, generally speaking i cannot see inside thier gills) He is pale around his face and gills but his fins and the back part of his body still have color. the 2 corys that are in the tank are still swimming around and doing whatever corys do, they do not seem stressed in any way. Water parameters tested normal and i used decholorinator and a tiny (and i mean tiny) bit of pH balancer in the tank when i changed the water just so i wouldnt shock the fish with the differing pH levels.
He does not seem to be bloated or to have any other outward signs of what can be wrong, i happen to noticed the inside of the gills when i was looking for him in the tank this morning, other than that and a little paleness everything else seems to be more or less normal. i have no idea what could be wrong. any help would be appreciated, thanks a bunch!
Incase anyone is wondering:
pH- between 7.0 and 7.5
nitrate- between 0-20 (typical results for me)