Help - what is this?

[Sheermiss]

Hi all,

I need some help identifying what went wrong with one of my Golden Barbs.

I noticed her tail fin was missing one Saturday (15/09). It looked like severe fin rot but this was the first time I had noticed it and I pay close attention to my tank. I thought maybe someone got aggressive during the night and bit it off.

We quarantined her and upon the advice of the LFS (we only take advise from one guy who knows his stuff) we began treatment with Melafix and Tonic Salt. Sunday I noticed small red "sores" or lesions on end of her tail stump. By Tuesday a big cotton looking ball surrounded where her tail once was. There also was a white patch on her back leading up to her dorsal fin and her dorsal was infected too with white growth (not cottony looking though).

She hadn't been eating and was swimming fine up until Tuesday night where she really began to struggle - swimming at the surface, sometime lying motionless on her side at the surface. It was at this point I decided to euthanise her. I doubted whether she could recover even if the infection cleared up as it had spread to her tail stump not just her fins and I couldn't bear to see her suffer.

Question is - what was this? None of the other fish have shown any symptoms.

Fin rot? Columnaris? Saprolegnia? Damage from injury and bacteria or fungus took hold?

The LFS tested our water and there was a small reading of ammonia which can be explained by a dead otto we couldn't find, nitrite and nitrate were 0

I tested our water parametres 2 days after a water change

Ammonia:0

Nitrite:0

Nitrate:0

PH: 6.8 - 7.0 (can never quite tell)

Nitrate is always zero, I know some say it shouldn't be zero in a cycled tank BUT we have a fair amount of plants.

Sorry for long winded post, see below for pic. Any help would be greatly appreciated.

[Sheepsnana]

I haven't seen that before.

I thought my Nitrate reading was 0, in a moderately planted tank, but it turns out the LFS needed to read their instructions a bit better.

[Caryl]

The big cotton ball would have been an opportunistic secondary fungal infection. Very common to develop over wounds. Often, after a while, you can knock or pull the fluff off and the wound beneath has healed totally.

Sounds like something bit the tail off but bit it too deeply for recovery. Usually fish can grow back tails quite quickly but if bitten off too close to the body this is not likely.

[F15hguy]

once it hits the caudal peduncle (the fleshy bit at the base of the fin) it tends to not grow back.

im sorry but it would be better to knock it on the head.

it is commonly caused in barbs by a small bite to the caudal peduncle just in front of the fins, sometimes it will heal but to be honest chances are very slim.

if you want to have a go though, try treating with methylene blue at a concentration that makes the back of the tank hard to see, and make sure you remove any carbon from your filter first.

[Godly3vil]

She hadn't been eating and was swimming fine up until Tuesday night where she really began to struggle - swimming at the surface, sometime lying motionless on her side at the surface. It was at this point I decided to euthanise her. I doubted whether she could recover even if the infection cleared up as it had spread to her tail stump not just her fins and I couldn't bear to see her suffer.

[Sheermiss]

Sounds like something bit the tail off but bit it too deeply for recovery. Usually fish can grow back tails quite quickly but if bitten off too close to the body this is not likely.

once it hits the caudal peduncle (the fleshy bit at the base of the fin) it tends to not grow back.

im sorry but it would be better to knock it on the head

I thought as much, good to know I didn't euth her in vain. Also just wanted to confirm it was a secondary infection and not something wrong in the tank! Meth Blue would have been my next step but I thought she was too far gone.

Thanks for the input