Hi all, first time poster here, but I've been lurking around these forums for quite a long time and as a betta enthusiast they've been immensely helpful to me in the past. :)
Recently I just 'adopted' a betta from someone I (vaguely) know through one of my classes, who (apparently?) bought it for his girlfriend, but then found out she didn't want it. I have a feeling the little guy would've been either mistreated or flushed otherwise, so I offered to take him. From what I can tell he's only been out of the petstore for a few days, and I have very little information past that.
Problem is: as soon as I got him, I found out this little guy has tiny holes all over his back fin, and a little bit of a hole-shape at the end of his bottom fin. The edges of his fins seem to be fine, and there isn't any discoloration on his fins or his body. The holes don't look 'ratty'-- they're all maybe about a millimetre in diameter, and there are about seven or eight of them, but they don't look like bits of his skin are falling off (as it looked in the last case of fin rot I had to deal with).
Besides the holes, though, he's very lively, perky and responsive. As I mentioned, he's not discoloured-- he's a very beautiful blue colour-- his gills don't look red or swollen, his eyes are clear, and overall he seems very happy. He's in a clean, conditioned gallon-and-a-half bowl for tonight (we had some water already aged for water-change purposes-- this was sort of a last minute decision!), but he'll be moved to a five-gallon tank with some nice silk plants and a heater tomorrow morning.
So: thoughts? Is it fin rot? Did he get into a fight? Tail-biter? I've had some very bad experiences with fin repair medicine and am reluctant to use it again, so really I'd just like to know what you guys think it might be, and whether I can heal it without stressing him out.
What size is your tank? 5 gallons
What temperature is your tank? 80 degrees
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? None
How often do you perform a water change? We're going to try 25% every two days once he's in the tank, and then about 50% once a week after that.
What percentage of the water do you change when you perform a water change? see above
What type of additives do you add to the water when you perform a water change? Conditioner
Thanks in advance!