I was gone from work for 5 days and during that time, a coworker (who doesn't usually deal with the fish) decided to change the water in the betta tanks. She changed the water on Saturday and I came back on Monday. Turns out she used RO water with Prime, instead of either tap water with Prime or RO water with RO right and Neutral Regulator. Oops.
Anyways, one of the bettas is in really bad shape. I think I caught water mix-up problem in time for all the other bettas in the tanks, but this one is really badly off.
What size is your tank? 20 gallons
What temperature is your tank? 83º
Does your tank have a filter? Yes
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? 6 bettas in a divided tank (~3.3 gallons/fish; please keep in mind that this is a pet store!!!)
What type of food do you feed your betta fish? Hikari Bio Gold
How often do you feed your betta fish? 1x daily (3 pellets, again keep in mind that this is a pet store!)
How often do you perform a water change? every Monday or Tuesday, since our fish shipment comes in early Tuesday afternoon
What percentage of the water do you change when you perform a water change? 50%
What type of additives do you add to the water when you perform a water change? RO Right or Equilibrium for RO water, Stress Coat for tap water (water used depends on tap water pH, as it is unreliable in my town)
Have you tested your water? If so, what are the following parameters?
Hardness: I forget, can test in the morning if needed
Alkalinity: I forget, can test in the morning if needed
Symptoms and Treatment
How has your betta fish's appearance changed? Slime coat sloughing off, fin melt, rapid gill movement
How has your betta fish's behavior changed? Lethargic, no appetite
When did you start noticing the symptoms?
Have you started treating your fish? If so, how? 90% water change Monday morning (yesterday) using tap water treated with Stress Coat. Added additional Stress Coat this morning.
Does your fish have any history of being ill? No.
How old is your fish (approximately)?~4 months
What, if anything, can I do to help this betta? I've never seen a fish this bad other than the one who jumped out of the net into the sink (and there the slime coat issue made sense).