This is Kevin. I bought him a few hours ago from a local Petco, because I am far too poor to obtain a better fish from a breeder.
At first he was just sitting at the bottom of his bowl, which seemed peculiar to me for a fish who was suddenly given another full gallon to swim around in, so I placed him next to another of my bettas, where he became far more active and began to flare his fins. This is when I started to question what was wrong with the end of his tail, where there appears to be a chunk of fin missing with redder edges, near the center edge of the tail. So I ask, what might be the cause of this (fin rot?), and what might I do to fix it for him?
On another note, I've only really bought veiltails before, not much caring about specific breeds of betta since I keep them purely as pets, but would anyone be able to identify exactly what this guy is, since Petco mislabels them constantly?
I have him in a ~1 gallon bowl, I always use purified water, and usually just keep my tanks at room temperature (which let's be honest, is pretty warm in my house!) But he's only been with me for about 8 hours now, so whatever is up with his tail happened during his time at Petco, but I just noticed it now... Is it definitely fin rot? If I just keep him in good living conditions, things should improve?
It doesn't look like it is but fin rot escalates in bad water conditions. Your room would need to be around 80 degrees consistently to keep your fish without a heater, consistency being absolute paramount. Temperature fluctuations can harm their immune system which leads to them not fighting off small things a healthy fish can and will end up with problems. I would recommend getting a suction cup thermometer to put inside your tank so you can monitor the temp. Aim for 75-82 in stable conditions.
Fin rot on a light colored fish is easier to see. It will appear red or black. Clean, warm water is best but you can add something like API Stresscoat+ (a water conditioner) as well as it has aloe in it to aid in healing. There isn't much need to use purified water unless something is wrong with your tap water. If it's fine then I would suggest the Stresscoat, which I believe you can get at WalMart or Prime which PetCo and Petsmart have.
So for right now in a one gallon bowl I would do two 50% changes in a week at least to make sure it doesn't develop into finrot. Long finned bettas like HMs are really prone to tail biting during stress or boredom. Being in a small cup at the pet store is pretty stressful, I'd think. If you have any decor make sure that it won't snag his fins. I'd stay away from plastic, silk is usually best. If you aren't sure then run some pantyhose over it and if it snags then it will tear his fins.
He's a pretty boy and you're lucky to have found such a lovely fish!
He's actually an Over Halfmoon or OHM, his tail goes over the regular halfmoon or capital D shape. And yes that chunk was probably bitten out by him and then rot took it over.
Warm, clean water will be great for him. For a 1 gallon I'd actually suggest one 50% and one 100% change a week to keep him healthy but if you can only do the 50% that will be fine for now.
Whenever you use water from your tap you always have to use the conditioner, generally it's one drop per gallon with Prime and other's like API. But there are chlorine and chloramine in your tap along with heavy metals that can hurt your fish, so always condition!
Just keep an eye on his tail though, if he does get worse you can use 1 teaspoon of Aquarium salt (dissolved before you put it in) to help get rid of the rot and then Stress Coat will heal it up afterwards
It's pretty great hearing he's definitely a HM xD Not bad for a Petco find, especially considering he was labeled as a "delta tail" and was around $6 rather than the $20 they charge for what they consider "halfmoons."
And caring for the tail situation sounds simple enough- I'll keep his tank in great condition and hopefully things will improve. Was worried I might have to go seeking medication immediately.