So I had a happy tank until yesterday when out of the blue, one of my rasboras died. I hadn't noticed any of them being lethargic or otherwise acting ill. I also noticed that the alpha female of my betta sorority was showing stress lines.
This morning, one of my female bettas was super-lethargic, so I isolated her. She was white with red coloring on her fins, so if there were any white spots on her body, I would have completely failed to notice. She was dead when I came home this evening.
Now I have a fish finally showing a physical symptom. My male betta's mouth is white, more on the lips and inside than on the outside. He's still moving around the tank, but sticks his head much further out of the water when breathing than usual. Of my remaining females, two are now showing stress lines more often than not, and the third is white so I can't tell.None of the other fish in the tank appear to have anything like what my male betta has. The algae eater is actively foraging and the rasboras as shoaling (the water change freaked them a bit) and one was spawning earlier today.
Is this cotton mouth or something else? What else, besides salt, should I use to treat it?
What size is your tank? 29 Gallons
What temperature is your tank? Mid 70s (I don't trust the sticky thermometer on the side of the tank to be more accurate than that)
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? 3 (used to be 4) female bettas, 7 (used to be 8) glowlight rasboras, and a juvenile chineese algae eater
What type of food do you feed your betta fish? commercial pellets and flakes
How often do you feed your betta fish? once or twice a day
How often do you perform a water change? once a week
What percentage of the water do you change when you perform a water change? ~20%
What type of additives do you add to the water when you perform a water change? API Aquarium salt at 1T per 10 gallons (about half the amount recommended on the container)
Have you tested your water? If so, what are the following parameters?
Ammonia: 0.25 (but I just did a water change and kicked up some waste. It was at 0 this morning)
Nitrite: No test
Nitrate: between 20 and 40 (closer to 40)
pH: No test
Hardness: No test
Alkalinity: No test
Symptoms and Treatment
How has your betta fish's appearance changed? White around the mouth (2 of my females are showing stress lines but I'm not sure that's related)
How has your betta fish's behavior changed? Somewhat less active
When did you start noticing the symptoms? Today
Have you started treating your fish? If so, how? water change with the stock of water I had available (about 5 gallons) with 1T aquarium salt.
Does your fish have any history of being ill? No
How old is your fish (approximately)?I've had him about 2 months