My black ranchu has a lump at the top of his pectoral fin, where it meets the body. It's a perfectly round, black, lump, no discolouration at all. I tried to get a picture, but since he's matt black, and the lump looks to be under his skin and matt black as well, it's not showing up very well, especially since he's extremely wiggly :/
He's swimming normally as far as I can make out, but it is pushing his gill out a tiny amount when he swims.
I did recently add another fish to the tank who was a bit of a biter for his first few days, but he's settled down now.
I think he's had it about 5 days now, it's gotten a bit bigger in that time, at the start I was hoping it was just 'one of those things' - he's one of two very faulty chus that were the runts of the litter.
There's no colour at all underneath that I can see, just pure black, so I'm speculating that it's some form of cyst or tumour, (speculating all the way up to carp pox and cancerous tumours too).
He's a thrasher too, so when he's caught it's even harder to get a closer look at anything - I'm used to Ronnie who used to sit still once he figured out you were going to Fix the Thing.
If it gets any larger, do you think lancing it might be the way forward? Or I might just hang in there and see what happens :/
I think I'd be inclined to keep an eye on it for a couple of days. If it was an infection from outside you'd be able to see an entry point I'd have thought, it's so hard to say when these things pop up without so much as a by your leave Lancing it would only help if there was infection inside, one of mine had a cyst once and the vet drained it with a syringe. If it's a lump of any other sort you might just end up giving an entry point to an infection
Developments this evening - just had another look in the tank and this has either burst or been bitten - it's all pink and raw inside, again it'll be impossible to get a picture of ... I added melafix and pimafix, went searching for iodine but can't find it...
Don't panic Captain Mainwaring On the one hand any mankiness inside is no longer inside. Melafix and pimafix should help keep any infections at bay, you could also add some salt. If you can't find iodine (you want povidone iodine) you can use myxazin as a topical application as well. Same would be true for sterazin seeing as the ingredients are the same bar one. You would just use it the same as iodine; net him out, dab it on with a cotton bud, pop him back in.
Well he's still flapping it around and using it, so it can't be hurting him too much I think just keep an eye on it for the next day or so, keep the water nice and clean etc. He's still swimming about, if he wasn't happy he'd be lurking somewhere and not wanting to move around