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Discussion Starter · #1 ·
Hello all.

This as my first time here ... so please be gentle ;-)

I 'm a complete newbie with my tank setup. It's been up and running for just over a month and already I seem to have a problem with my Corydoras (Bronze Catfish).

A couple of our Corydoras seemed to developing bulging bellys, but now one fish in particular has a very prominent white lump protruding from it's side. It looks like it could be some kind of fungal infection ... or maybe an injury. We have no idea. Another Cory seems to be starting to show signs of a similar lumps in the same place.

The fish themselves seems to be behaving totally normally, swimming and digging without any noticeable problems.

I have filed out the 'form' below (as well as I can) and have attached a few pictures of the patient too.

Does anybody have any idea what what might have on our hands here .... and how we should tackle it.
We would appreciate any input or advice anyone might have to offer.

Thanks in advance and greetings from Cologne Germany.
Philip & Maren

1. Size of tank?

2. Water parameters
a. Ammonia? 0
b. Nitrite? 0
c. Nitrate? 10 mg/l
d. pH 8, KH 12 and GH 25 (we live in a very hard water area)
e. Test kit? Sera test box kit

3. Temperature? 25 deg cel

4. FW (fresh water) or BW (brackish)? Freshwater

5. How long the aquarium has been set up? 5 weeks

6. What fish do you have? How many are in your tank? How big are they? How long have you had them?
3 x Pitbull Pleco
5 x Corydoras (bronze) catfish.

7. Were the fish placed under quarantine period (minus the first batch from the point wherein the tank is ready to accommodate the inhabitants)? The fish were introduced together as the fist inhabitants of the tank. The tank was set up and running for three weeks before the fish arrived.

8. a. Any live plants? Fake plants?
various live plants.

b. Sand, gravel, barebottom?
JBL Manado & sand on one side

c. Rocks, woods, fancy decors? Any hollow decors?
Wood piece (the Pitbulls love this)
Small cave / shelter

9. a. Filtration?
Jewel super filter (internal corner filter)

b. Heater?

10. a. Lighting schedule? What lights are used?
10 hours per day, tube supplied with tank.

b. Any sunlight exposure? How long?

11. a. Water change schedule? Weekly
b. Volume of water changed? 15L
c. Well water, tap water, RO water? Tap water
d. Water conditioner used? Tetra Easy Balance
e. Frequency of gravel/sand (if any) vacuumed? Not yet done

12. Foods?
How often are they fed? daily (1 tab)

13. a. Any abnormal signs/symptoms?
b. Appearance of poop? normal ... I think
c. Appearance of gills? ok .... again I think

14. a. Have you treated your fish ahead of diagnosis?
b. What meds were used?
none yet.

15. Insert photos of fish in question and full tank shot if necessary.


3,553 Posts
my large lou han had a lump like's most likely a parasite thats causing it.i dint use any medication i just kep the water cleaner then usual and it slowly might want to get an external water filters are that good but thats imo

1 Posts
I have exactly the same problem with my Cory's! Have had many tanks over the years but by no means an expert! Hopefully someone with more knowledge and experience can help 🤞

Hope your Cory's are okay!

28 Posts
My betta fish had a similar lump. I’m not sure if you can treat bettas the same way you treat Corys but aquarium salt eventually helped my betta.
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