Ulcer on lateral fin

1. Please explain the problems with your fish. When did you notice the problems and did anything unusual happen that you think started them?
One week ago, noticed a small white spot where the lateral fin joins the body. I think the behaviour of a laying pair in the tank - territory defence, aggression, and the fact that the female of the pair used to pair with the affected male, has caused some significant stress for him. Also fighting between the paired male and the affected 'jilted' male. The spot has grown, and is an ulcer.

2. Symptoms (i.e. turning dark, excess slime, not eating, clamped fins, flashing, darting, clamped gills, white/yellow/green poop, hiding, headstanding or tailstanding, white on tips of fins, rotting or fungus, blisters/white zits on fish, bloated, cloudy eyes, wounds).

Single large ulcer, with some reddened rough looking area directly below it. However, he is eating, pooping right colour and consistency, not gasping or hiding or clamped fins. No pitting apparent.

3. What medications/ treatments have you already tried and what were the results. Include dosage and duration of treatment.

Whilst still in the main tank, I pulled him to a net and swabbed the ulcer - it burst and pus came out. Swabbed with hydrogen peroxide. Ulcer re-formed 3 days later. He is now in a quarantine tank. No further meds or treatment, just daily water changes and tank wipedowns.


Tank/Water

4. Tank size and ages, numbers and sizes of fish.
Main tank: 850 litres (~220 gallons). 250 litre (~62 gallon) sump. 5 adult discus aged between 2.5 years and 5 years, 14 sterbai corydoras, aged between 6 months and 1.5 years.


5. Water change regime (What percentage and how often).
30% every 4 days (more often if the husband isn't home, heh). Vacuum of waste every other day.


6. How long has tank been running? Is it bare bottom? If you have substrate, what type and how deep is it?
~2 years running. Thin playsand substrate - very thin - around 0.5 cm.


7. Do you age your water? If you do for how long and what is the ph swing.
Yes. Anywhere between 12 to 48 hours. pH swing is downward (rainwater) to 4.8.


8. What type/brand water conditioner do you use? Do you add it to the tank or aging barrel? How much do you use?
Seachem prime. Added to barrel. Standard dose as per instructions on bottle.
Also remineralise the aging barrel water with a mix similar to Seachem Equilibrium that I make myself (recipe from this site), which brings the TDS to around 120 and the GH to 4.


9. Parameters and water source;

Note: Water Parameters are important in diagnosing problems within a tank. If you don't own test kits for the following information, you can purchase them, test your parameters and post this info as soon as possible.


- temp: 29 degrees celcius in both tank and aging barrel

- ph: 6.3 in tank in the evenings, can be 6.1 in the mornings.

- ammonia reading 0

- nitrite reading 0

- nitrate reading 20

What type of water or combinations of water sources do you use? If it is an RO/tap/well water mix, please list percentages in the mix.

Rainwater


10. Any new fish, plants or inverts added recently.
No


11. Please tell us what you feed your fish and how often. This can be critical information for solving the problem so be as specific as you can.
- A homemade fish-based recipe containing fillet fish (trevally, warehou, or terakihi); shrimp; mussels; eggs, banana, spirulina, krill oil, sheep liver (this time, instead of beef heart), garlic, vitamins, cooked spinach leaves, salmon, mushy peas. They all eat this.
- Hikari discus pellets, Sera pellets, mysis shrimp (frozen), bloodworms (frozen). This food is only accepted by 2 of the 5. I have been trying for months to get them all to eat these less messy foods, offering them as the first meal of the day. They're not keen.



12. Include any pictures or videos you have which shows the symptoms. If you can't add them to this post, please provide a link to them.

I apologise for picture quality - I have tried multiple times to get something better, but I'm no photographer.
Attachment 125588

Hi Cate.
Sorry about your troubles. Are your nitrates 20 before or after water change?
Cheers,
Danny

Hi Danny, thanks for responding. Nitrate reading should actually say <20 - as in, I can't discern between the 10 and 20 colour. However, that was before last WC in main tank (where there are also a ton of floating Indian fern).
C

Just regarding the rainwater entry from the aging barrel to the tank. IS there any sort of sediment/chemical/bacterial filter used? I am wondering as I know rain water tanks can host some nasty bacteria, and need to be filtered out even for human consumption.
I am not saying this is causing it, but may not be helping?

Cate my thoughts are that if your nitrates are at or about 20 after 3 days of a 30% water change you nitrates are never <5-10 which is the ideal maximum nitrate level which promotes good discus immunity & health. The other factor which is not measurable is the bacterial/pathogen counts. With the higher temps discus require bacteria/pathogens multiply at a faster rate, so with small wc's only 2 times a week, your counts will only every be increasing. The problem you are experiencing could be a combo of weakened immunity and high bacterial counts. My recommendation is to do a series of daily wc's, say 50%, adding 4-5tbsp/10 salt, replacing what you remove with each wc. Once the wound heals with lots of clean water & salt, change your routine to 50% every 3 days if possible.
As Brendan mentioned, is your rain water storage a large outdoor tank or a smaller barrel? Is that water only used for your wc's? If so, you could salt the storage tank to reduce bacterial pathogen counts in your source water.