ok i am new to owning bettas. i love them. but my first one died of ich. i have 4 bettas now. 2 in a 5g and 2 in a 10g. well 2 of them have ich. and 1 of them is sick but can't tell what it is. he looks normal has all color but he is lathargic and stay flat at the bottom, comes up for air then stays by the thermometer and back down again after a while.
i have done ich treatment on the 2 with ich. all 3 fish that are sick i have had under a month, bought at different times within the month. my oldest which is maybe 2 months has nothing wrong with him other then he is a mean betta
i have heaters in both tanks, filters, lots of plants with caves, thermometers. filters.
i have a test kit. water is crystal clear, all levels are in the good
what am i doing wrong