I've noticed a vertical cut on my gf fin on its back.

the fin was one. now its cut into 2 parts...

why?

Well, Surely, we are going to need more info than your description of the split.

Try answering every one of the questions from the box above this thread. Once we get that info, we will be better able to help you figure this out.

Paul

Ammonia Level: unknown, waiting for a test.
Nitrite Level: 0
Nitrate level: 0
Ph Level: 7.8
Ph Level out of the Tap:
Tank size: 14g
How long has it been running: 1 month
Filtration: 1 canister (132g/h), 1 power (80g/h)

How often do you change the water and how much?
~30% every 3-4 days.

What kind of Water additives or conditioners?
Tetra AquaSafe
Tetra EasyBalance
Tetra FloraPride

Any Medications add to the tank?
No

How many fish in the tank and there size?
1 common (2,7 inches)
1 fantail (2 inches)
[tails included]

Add any new fish to the tank?
No

What do you feed your fish?
gel food, peas, flakes, fresh bloodworms and fresh brine shrimp and frozen shrimp

Any unusual findings on the fish?
bloody streaks

Any unusual behavior?
stressed when i approach the tank, sometimes gasping air from surface.


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It's like somebody cut it with scissors.

The webbing between the fin supports are quite delicate. If there are no obvious sign of disease or fungus, then it is most likely trauma like running into a sharp object or sharp, sudden movements. Did you try to net the fish? That can split the fin as well. That type of damage should heal naturally if there are no further complications.

no i didnt try to net it... in my tank there are plants and round rocks. nothing sharp.
i hope thats caused from a sudden movement...

My fish sometimes get that too. Often there are signs of stress on other fish in the tank, like a split tail or white marks on their tail fins. These symptoms generally relate to water quality and I currently have different fish showing these different symptoms in the 40g where I lost Queenie and BlibBlob a few weeks ago. There was also a problem with fish lice in this tank too.

Although the water parameters in my 40g are fine there is obviously a bacterial inbalance there and it is stressing my fish.

All I suggest is regular (even small daily) water changes and salt. Vertical splits in the dorsal fin have healed in 3 days with this method.

Have you medicated your tank recently? This could cause an inbalance.

no. never medicated!

Hopefully Im am going to install a UV sterilizer this Monday. Maybe that helps with bacteria... rite?

My female split her left arm fin during spawning. It is completely healed by now.

OldHag

The UV sterilizer will help with algae. Not so much the bacteria.

What will help you with the bateria is ether the Peguin, or the Emperors because they (marineland) invented the bio-wheel which will cultivate the bateria.If you had asked me, I will recendmend the Emperor 400 .