bacterial or traumatic fin rot?

[GrahamC]

I'll add in all the details though some may be superfluous.

This is regards to my 160 L tank with 1 Oranda, and 4 other small goldfish that I've had for several months.

I came back to my apartment on Monday night after a 4 day absence to find the tank nearly opaque and green with algae. It was clear when I left and I had vacuumed before I left. Checked water quality and Ammonia, Nitrite and Nitrates were 0. Vacuumed the gravel again and removed lots of faecal material. I installed a sponge filter I picked up from the Levin pet shop ( seems they had a disaster over the weekend .. several tanks had cracked and emptied their water over the floor ).

The next day I came back from work to find my Oranda trapped inside a castle ornament. I thought she had died but she was okay, but had lost some scales from both sides. I didn't look at her tail at all.

Yesterday when I got back from work I now noticed my Oranda had ragged anal fins in the lower 2/3. The other fins seem to be okay, and she is swimming and eating fine. I feed them gold fish flake and duck weed.

I decided to change my HOB for a new cannister filter I had bought from TM. It's a Sunsun HW-304B that does 2000L/hr that I had bought in preparation for setting up a larger tank. The seller had included charcoal, bio balls etc. I transferred the biomax into the cannister, threw the sponge from the HOB into the tank and started the filter. I also turned on the UV light, did another 25% water change and gravel clean and added some aquarium salt.

This morning the tank was much clearer, and she is still swimming well. I went to my LFS who suggested I use some API Melafix which I obediently bought. However, after a bit of reading, I find that fin rot is caused by bacterial infection which causes infarction of the fin, and perhaps I should be using a systemic antibacterial agent. But it can also be caused by trauma and fungal infections.

I took a video from my camera http://youtu.be/bQCTiAMSEAY to show her tail.

So, I'm not sure what I should do. Isolate her into another tank ( none ready ) and treat with Melafix or some tetracycline, or just hope the water changes and salt help.

[Adrienne]

I have no experience with oranda or coldwater fish but if it is not bacterial, salt and keeping the water pristine will do the job.

If bacterial and it is fin rot you will see fine red vein like lines form above where the fins/tail end. This is where the next lot of fins/tail will fall off to and the red vein like lines will form and it will continue on and on until nothing is left.

I would try the salt first and if it deteriorates further then you will need to use something stronger.

[Caryl]

The top of the tail looks fine, it is just the middle bit. There are no red streaks either so I suspect damage more than fin rot. Excellent water quality is the answer.

I am a little intrigued you have 0 nitrites AND nitrates. There ought to be some nitrates in an established tank as the tap water will have them.

Goldfish are poo machines and produce a lot of waste. A combination of different types of filtration is best as they can disturb the substrate and cause a lot of floating matter in the water column. An external plus the HOB is good. You will find you have to clear the sponge regularly though as it will clog quickly.

[GrahamC]

I thought there should be nitrates as well to get that algal bloom but the test tube colour was light blue indicating 0 nitrates.

I am thinking I should ditch the stones and go for silica sand instead. Much easier to see the waste material.

I not sure why a HOB and external would be better though. Is it because one drags in water from the bottom, and the other from the mid level? Today water is clear and the caudal tail fins are no worse. I can't see the anal fin because of the other fins are obscuring it.