Rasbora disease

[meadoughlark]

12 gallon planted tank, 25% water change weekly, ammonia 0
Original population: 10 lambchop rasboras, 1 dwarf gourami, all bought half a year ago

Just over 3 weeks ago I noticed that one of the rasboras had a white patch on its side. When viewed from above you could see that it's tail was kinked to one side:

Another rasbora was pale in colour, but no white patch or kink, and feeding fine. All of the other fish were fine.

I noticed this a few days after an 8 hour power cut at my house, which happened while I was at work. I live in Thailand so the still water would have gotten quite warm and oxygen levels would have been low without circulation, possibly allowing some nasty bacteria to grow?

I euthanised the 'bent' fish and treated the tank with an ich and columnaris treatment over the next 4 days. I left the pale one alive but a few days later found it stuck behind my surface skimmer, I guess it floated there in its weakened state. I freed it and when it was still swimming sluggishly the next day, decided to euthanise it, fearing something spreading. I did wonder if getting stuck behind the skimmer might be a common occurrence, and the 'bent' fish might have injured itself when freeing itself. Seems unlikely though?

The remaining 8 rasboras and the dwarf gourami have been absolutely fine for the last 2 weeks, but today I've noticed a rasbora with the exact symptoms as the first - white patch on one side, kinked tail. Any idea what's going on? 'Fish TB'? Should I treat again and euthanise victim number 3?

I haven't added anything new to the tank that could have caused the infection, but I did set up a new tank for celestial pearl danios last month and stupidly have been using the same siphon for both tanks, which could have caused cross contamination. The danios are fine though.

 

[Salty&Onion]

Its not TB, don't euthanise the fish. Its fungus, I suppose caused by poor water quality with small tank and huge stock. 12 gallon tank is too small for both fish species, get a 20 gallon long, tank must be long for rasboras as they are quite an active fish.
1-2 heaped table spoons of aquarium salt per 20 L should clear up the fungus. Keep the salt in the tank for 2 weeks.
Give your water parameters in numbers for ammonia, nitrite and nitrate.
The siphon won't cause cross contamination.

 

[Essjay]

The siphon won't cause cross contamination.

Cross contamination can occur with diseases like whitespot and worms amongst others unless the siphon is allowed to dry out totally between tanks. Any drops of water in the siphon can contain whitespot parasites, worm eggs etc.

I have two tanks, two buckets, and two siphon tubes.

 

[Retired Viking]

I agree with the other posters and I would try and get a larger tank. If you are in the USA Petco has their 1 dollar per gallon tank sale, A 20 gallon long would be a great tank for your Rasbora. I have one and it is easier to maintain than the taller tanks and gives your fish the room they need.

 

[JuiceBox52]

I agree with the other posters and I would try and get a larger tank. If you are in the USA Petco has their 1 dollar per gallon tank sale, A 20 gallon long would be a great tank for your Rasbora. I have one and it is easier to maintain than the taller tanks and gives your fish the room they need.

They are in Thailand, but good suggestion

 

[meadoughlark]

Thanks for the replies folks.

Its not TB, don't euthanise the fish. Its fungus, I suppose caused by poor water quality with small tank and huge stock. 12 gallon tank is too small for both fish species, get a 20 gallon long, tank must be long for rasboras as they are quite an active fish.
1-2 heaped table spoons of aquarium salt per 20 L should clear up the fungus. Keep the salt in the tank for 2 weeks.
Give your water parameters in numbers for ammonia, nitrite and nitrate.
The siphon won't cause cross contamination.

I will upgrade to a 20 gallon when I can. My tank is over-filtered, I use an Eheim 150 external filter on it, ammonia is always 0, nitrites 0, nitrates aroun 10mg/l. But I know that doesn't make up for the space issue. I've had a big trim of the plants in the meantime to give them more swimming space.

I went to my fish shop for aquarium salt, they asked me if I wanted salt for medicine or saltwater aquarium salt. I said medicine and got this stuff. I assumed it was just aquarium salt in a smaller package than the big boxes that saltwater aquarists get. But I put it in the tank and it turned the water green, so there must be some other medicine in with the salt. The instructions say use 1 tablespoon per 15l. My tank is 45l so I should use 3 tablespoons, I've just used 2 for now because the green freaked me out. My Thai friend says the label says 'aquarium salt with tetracycline'. I know tetracycline is antibacterial so won't have an affect on fungus, but hopefully the salt component will do its job. How long can I leave this in the tank before water changing? Will the tetracycline kill my filter bacteria? I really need to learn Thai. Other than dose, there are no directions apart from 'use with every water change.'

For future reference, how do I tell the difference between fungus, ich, and columnaris?

 

[Lajos_Detari]

Here are some info for you

Fish Columnaris | Fungus & Saprolegnia | Treatment & Prevention

www.americanaquariumproducts.com

 

[seangee]

I suggest you increase your weekly water changes to 75%. There is no need to stop water changes while treating. When you do your water change add enough salt for the new water you are adding - so if your water change is 30l then add 2 tablespoons.
Tetracycline is an antibiotic but we have no idea about the concentration. It may well affect the bacteria in the filters. Based on your photos you have enough plants that this won't be a problem - as long as you haven't been too extreme in trimming them