So, I have had this one male Betta for 4 or 5 months now. Everything has always been fine. He was making bubble nest, eating all the time.
He live in a 3 gallon LED tank, with a rock, driftwood with moss, and some live plants. Tank is kept around 80 degrees. Water params have always been fine.
A month ago, I suddenly had a spike in ammonia and nitrites. I test weekly. I noticed he seemed a little odd that day and tested the water sooner than weekly, and noticed the spike. Immediately got him out into a transport tank I have. Changed the water 50% everyday for 3 days until I got the spike under control.
He seemed fine, kept eating, kept being himself. He had to stay in the small transport tank (think it is like 2 cups) for those three days. When I put him back in the 3 gallon, he was fine. Tested the water every other day to monitor the situation. I had some fluctuations in the ammonia at .25 PPM, but I didn't think that was a huge danger to justify keeping him in the smaller tank. Continued to do 50% water changes once or twice a week.
However, something changed about a week ago. He stopped making his bubble nest. He stopped being friendly, and anytime you even get near the tank he goes and hides. He still swims around a bit when no one is near the tank, but not as much. He was still eating, but today he seemed to stop. He used to come right to the top to eat, now he doesn't and the pellets sink to the bottom.
Any idea what I can do? I just changed the water again last night because there was another slight spike in ammonia, at .5 PPM. No nitrites, low nitrates. I had changed the filter cartridge in the tank 3 or 4 days ago, and i have left the old cartridge in the tank for a few days (still in there now).
Am I missing something? AM I not paying attention to something?