Help [Black Wolf Fish Fin Rot] Cannot Solve

[Regency45]

Have you tested your water?

Yes

If yes, what is your ammonia?

0

If yes, what is your nitrite?

0

If yes, what is your nitrate?

0

If I did not test my water...

1. ...I recognize that I will likely be asked to do a test, and that water tests are critical for solving freshwater health problems.

Do you do water changes?

Yes

What percentage of water do you change?

51-60%

How frequently do you change your water?

Every two weeks

If I do not change my water...

1. ...I recognize that I will likely be recommended to do a water change, and water changes are critical for preventing future freshwater health problems.

Hi, I have a black wolf Hoplias Curupira.
BACKROUND -
-I got him 6 months ago, he was 3 inches, looked great active no issues. He is now ~8 inches
-At 2 months I saw my filter wasn't sufficient, so I swapped for fx6 filter as well added black sand to help with reflection.
-Few Weeks later fins looked rough, began to monitor, within a week fins deteriorated seemingly overnight extensively, especially front two and sides.
-Immediately freaked and called place i bought from, started kannaplex as recommended and removed black sand, on my own accord afraid it could have leached something though it was washed.
-At this point i only had two pieces of wood and fake plant. Fin rot stopped completely and regrowth began.
- Regrowth for last 2 months has come and gone, not getting worse but starts to regrow then the new growth disappears and restarts.
-Fish has grown to 8 inches and is very happy, eats well, great personality, confident, aggressive, so signs of any issue.
- I just now removed logs due to thinking possible brushing against may be issue? I replaced with a couple smooth stones for his focal point.
- Flow is also dropped now although before i had plant stuffed in outlet to kill flow after now removing plants i have cut the flow in half it is smooth and slow he can rest on bottom without issue, I also have a bubbler for aeration and tank gets good slow flow throughout.

SETUP-
-75 Gallon Bare Bottom
-Fluval E300 Heater, was at 80 recently brought down to 78
- Bubbler
- Couple Smooth Stones
- Low Dim light and blacked out sides.

I seriously don't know what to do at this point I'm really concerned for his front fins because they are just before the base, he hasn't gotten worse and i see some regrowth always happening but no progress, tank water is always clean i do pretty frequent water changes due to him being a predator, tank has no ammonia as i have the fx6 and 75 gallon with just him and am on top of keeping clean. He literally shows 0 signs of stress is confident, eats well, is not jumpy, IDK what can be the cause, if anyone has any insight it would be greatly appreciated. Note picture he just ate a chunk to tilapia and has no digestive or stomach issues.

 

[danotaylor]

It sounds like you had a mini-cycle to me. It would be helpful to know if you were testing your water, or just thinking that because he was the lone inhabitant with a big filter, that the water was "clean". When you removed the black sand, you also removed the majority of the surface area the beneficial bacteria grow on. Fin rot & ammonia burns can look very similar...
Questions;
Was the initial set-up brand new with the smaller filter when you got the wolf?
Did you ever test water parameters to know if your system was fully cycled?
When you saw the filter wasn't satisfactory & changed to the FX6, did you transfer the mature filter media from the old filter to the FX6 or just start fresh with the new FX6 media?

 

[Regency45]

It sounds like you had a mini-cycle to me. It would be helpful to know if you were testing your water, or just thinking that because he was the lone inhabitant with a big filter, that the water was "clean". When you removed the black sand, you also removed the majority of the surface area the beneficial bacteria grow on. Fin rot & ammonia burns can look very similar...
Questions;
Was the initial set-up brand new with the smaller filter when you got the wolf?
Did you ever test water parameters to know if your system know fully cycled?
When you saw the filter wasn't satisfactory & changed to the FX6, did you transfer the mature filter media from the old filter to the FX6 or just start fresh with the new

I was also doing small water changes of 5-10 gallons a couple times a week to siphon out any waste that wasn't grabbed by filter, (reason I said was clean). Also, first added fx6 then sand around a week later, then the fin issue presented itself around the following week from the sand, which was then pulled. Net sand was only in for about a week.

Was the initial set-up brand new with the smaller filter when you got the wolf?
--Setup was fresh biologically, was a past setup that was sitting dry for a month. Ran tank for 2 weeks with seachem stability before I got him, added prime in when i got him. Added small amount of food in tank for the initial 2 week before he came, ensured no ammonia present when he was added.

Did you ever test water parameters to know if your system was fully cycled?
-- I had the ammonia and nitrite testers in tank that are continuous. I also tested with strips near daily to confirm accuracy. Never showed ammonia or nitrites at any time.

When you saw the filter wasn't satisfactory & changed to the FX6, did you transfer the mature filter media from the old filter to the FX6 or just start fresh with the new.
-- Filter wasn't substantially deficient, whale 300, wanted to has slightly more turnover as well as more room for bio media due to bare bottom. I transferred all of the bio media to the fx6. Bimedia was 2/3 slots I did not transfer the Sponge.

 

[danotaylor]

Never showed ammonia or nitrites at any time.

This is very concerning in a new system. Did you measure for nitrates?

 

[Regency45]

This is very concerning in a new system. Did you measure for nitrates?

**For when he was in tank, should have clarified. Had nitrites and some nitrates a couple days before i got him. I did a Water change so they weren't readable for before I put him in. I was doing frequent small water changes and sucking out excess waste to prevent any spikes when i got him since I was expecting the bio to still be maturing, he was 3 inches then so he wasn't eating a massive amount.

 

[danotaylor]

Ok. Nitrite is a clear signal for an incomplete cycle.
Salt at 1tbsp/5gal will prevent nitrite poisoning and also reduce bacterial counts in the water column. I’d do that for 2-3 weeks replacing the concentration lost with each water change.
In the absence of any further fin rot (he looks good now in the pic w healing fins) I’m still thinking it was ammonia burns from a mini cycle when you added him. Some folks will trim the caudal fin so that it grows back evenly, some just leave it. That’s gonna be solely up to you mate