I lost one of my bettas yesterday. I got her 6 months ago. I have no idea what happened. She was perfectly healthy. Tested the water and all was fine. She was eating, swimming, etc...only thing I could possibly think of was temperature shock (keep my females outdoors in the summer - separate 3+ gallon tubs and daily water changes - water stays at 80 degrees) but none of my other girls have any issues whatsoever. I buried her in the backyard. This stinks.