I have kept bettas my entire life. I've gone a couple years without them, but in the past I was lucky and never had a betta get a disease. Unfortunately that was not the case recently. I purchased a 5 gal
Chi and a cycled it. I purchased a betta. I tested the water- no ammonia, no nitrates, no nitrite, PH mid 7s, Water hard, temp 77 and acceptable alkalinity. Tank matched betta's store water closely, so I put the betta in, he was a little stressed due to the current.
Fine for a month, then very fast case of columnaris. Over night it grew and in the morning he was suffocating, the columnaris had almost entirely encapsulated him, I treated with antibiotics, but too little too late.
Then I had to disinfect my tank, substrate, etc. I boiled and baked everything.
I purchase betta number 2. Tank is cycled, etc. Put in betta #2 and he is good for two days. I find him hiding, I take him out and look at him under the light. Columnaris AGAIN! I immediately test the water (hardness outrageous) others alright or same except the nitrate was around 5ppm
Columnaris can thrive in water with alot of minerals so I decided to opt out of the tap water. I ran to the store got spring water, drinking water and purified water (12 gals). Took tank water and made a high concentrated bath of antibiotics in a cup, placed betta while I made a mix of water and added some baking soda to bring ph up to a 7.0. Added Maroxy, Marcyn-Two and Marcyn in proper doses. Put Betta back in tank after an hour and observed. Betta was really sick, and columnaris was growing rapidly, so I opted for some dreaded salt dips (3xs) an hour apart. After each salt dip, betta started to behave and move around more. Every day I added the appropriate dosage of Maroxy, Marcyn-Two and Marcyn. (since filtration affects the level of antibiotics/ can filter them out I also added extra sprinkles about 1/12 of a dose of Marcyn and Marcyn-Two per day. I also directly applied salt water with a q-tip to the worse part of his anal fin. Betta is looking GREAT, vibrant, colorful, active. Now I'm just waiting for the tissue to heal from where the columnaris ate it's way through!