black mark on a rummy nose tetra

Question

sick rummynose   QUESTION: Hi there,

I hope you can help me! I have a relatively new tropical freshwater aquarium which has been going for 6 weeks now. It is a 130 litre AquaOne 620T, with a filter in the hood unit. I have since read some negative comments about hood filters, so I am keeping a close eye on my water parameters, and am considering supplementing it with an external filter. (Any advice on this would be appreciated too!)

After cycling, I have introduced some fish over a few weeks: 2 very small bristlenose catfish and 10 rummynose tetras in total so far. I've been doing weekly 20% water changes

Everything has been fine, except in the last week days one of the tetras suddenly has a very dark (black) mark on his left side, under his dorsal fin, which has formed a slight lump. It looks like the darkness is internal rather than a skin discoloration (it can actually be slightly seen 'through' him, looking at him from the right side. Then a few days ago, a superficial white patch over the middle of the internal black lump appeared. It is quite obvious and nasty looking, and a bit 'cottony' looking, so I suspect it's fungus?
He seems fine otherwise though, schooling and swimming freely, not  hiding at the bottom or breathing heavily, feeding normally, fins in good condition, and with good coloration. No itching or abnormal behavior at all.

All the other fish seem fine too, no marks or any sign of illness.

The water is clear, my  ph is 6.8, ammonia is 0, nitrite is 0, nitrate is 0, temperature 27 degrees.

Do you have any idea what this could be, especially the internal black mark and what can I do??

My local fishshop has advised melafix + pimafix together to treat what appears to be the white fungus, but I am concerned about the internal mark which was there first.

Thanks for your help!

ps - sorry, that was the best photo I could get of him. I hope it helps.

ANSWER: Please don't use Melafix of Pimafix, they're garbage and won't treat this parasite...it's a fluke.  It lodged in the skin and it will breed and make things much worse if not nipped in the bud asap.  Put the fish in a hospital tank (you need one of these anyway, so no better time to start a little 5 gallon hospital than now), and add 2 teaspoons of salt per gallon, dissolved, to that tank.  Heat it, make sure water is appropriately dechlorinated, and bathe the fish in the saltwater for about 24 hours.  Take him out and then returh him home once he's done bathing in saltwater, but please, be very careful.  Rummynose are quite sensative.  

The tank is very pretty, by the way. :)

Happy fish-keeping.

---------- FOLLOW-UP ----------

QUESTION: Oh! Thank you so much!! I was thinking maybe a tumor, but didn't consider a fluke.

Hospital tank coming up...

Is there any risk of my other rummynoses having caught it too though? Could the parasite have escaped into my aqaurium in general? And is the white 'fungus' looking but just growing on a wound caused by the fluke? Will the salt treatment cure that too?

Thanks so much for the quick reply, and sorry for the extra questions.

Answer
The image is small on my computer, so it's possible it is a fungus, either way, salt's the answer.  It's going to take care of that infection or parasite.  Either one is contagious.  I'd be very concerned if it's a fungus.  Watch the other fish.  Change water as frequently as you can (once every 2 weeks for awhile while the tank finishes its cycle throughout the next two months) and then once a month after that.  I'd change at least 20%, but not much more than 25%, so stay within that amount, so you don't shock the fish.  No panicking...this fish should also be returnable to the petstore, but it probably will die there.  Most stores have policies to cover sick fish.  If it should die from treatment or something, you can always freeze it, keep it in a baggie, return it for a new one. Of course, the idea is for the fish to recover! But you never know.

Happy fish-keeping.