One of my bettas died due to columnaris, and I feared it would be transmitted to the other one (since I unknowingly shared supplies between the two). I added a few drops of Melafix and Primafix to each fish's container as the Pet Smart guy said since the amount I should add adjusted for my container size (~600ml and ~400ml). Unfortunately the fish with columnaris died and soon the other one started acting sick. Not eating and it seems like slight fin rot (the edges are black). Once I immediately changed the water, the remaining betta perked up and it dawned on me that my previously perfectly healthy betta may be having problems with the medication.
Now that I figured out what's wrong with him, he's still not eating. He tries, then he spits it back out. He's been on a hunger strike for 2 days. I'm a bit concerned even though they can go without eating for 7 days.
What size is your tank? 2.5 Gallons
What temperature is your tank? 78F
Does your tank have a filter? No
Does your tank have an air stone or other type of aeration? No
Is your tank heated? Yes
What tank mates does your betta fish live with? He lives alone.
What type of food do you feed your betta fish? HBH Betta Pellets
How often do you feed your betta fish? 2 times a day, max 4 per feeding but I'll take out the food if they don't eat it within 3 minutes.
How often do you perform a water change? Everyday so far.
What percentage of the water do you change when you perform a water change? Initially when I brought him home, 50% changes - now it's 100%.
What type of additives do you add to the water when you perform a water change? Aqueon Betta Bowl+, API Stress Zyme+
Symptoms and Treatment
How has your betta fish's appearance changed? The yellow coloring he had grew darker. He keeps his tail fin clamped tight (but not as much now that I took him out of the medicated water).
How has your betta fish's behavior changed? He went from not moving, staying at the bottom, flinching when trying to breathe air, to calmly swimming around although still not moving much in the new water.
When did you start noticing the symptoms? I noticed it once I put in the Melafix and Primafix as a precaution.
Have you started treating your fish? If so, how? I took him out of the laced waters.
Does your fish have any history of being ill? He's spankin' new. So I don't know.
How old is your fish (approximately)? I've had him for a week, but he looks young. He's a halfmoon though his tail isn't fully developed.
My problem now is if there will be any lingering adverse effects with the medication and how to get him to eat again. I only jumped to use primafix and melafix because the forum noted that it was a trusty medication.