Possible fin rot or fin nipping? What is the best course of action?

[Karine1995]

Good evening all! I have a long fin danio that I noticed today has his back fins separated into three parts, all my other leopard danios don’t have fins like this so I got concerned and separated them from the others in my quarantine/hospital tank. I checked my water parameters and my ammonia levels were in between 0.25ppm-0.50ppm which I immediately did a water change and added an instant ammonia neutralizer. My filter has now been running for a month and the cartilage was pretty black and it has been giving me the sign to change the cartilage for over a week now. Since it hadn’t been four weeks yet I didn’t change it until today as I thought that could also be making it worst.

I know a good chunk of the beneficial bacteria live in the filters so I kept that in mind and added some of the bacteria starter I had according to my gallon which is a 29G holding about 24G of water.

I am wondering if for my little leopard danio (long fin) if there’s anything I can do for them. I haven’t noticed my other fish have anything similar to this fish yet which is why I separated him. I will attach a slow motion YouTube video of my fish swimming as well as a screenshot from the video where you can see the fin Separated into three parts.

I really like my aquarium and I’m trying to be a good aquarium keeper.

Here’s the YouTube video:

Thank you ahead of time for the help!

 

[JuiceBox52]

It looks like fin nipping to me. Keep up with the large weekly water changes. Ammonia above zero is toxic to fish.do any other fish appear to be picking on it? How many danios do you have? In too small of numbers these fish can become very aggressive with each other and other fish

 

[Karine1995]

I have 6 danios (3 zebra 3 leopard long fin counting with the one I removed from the tank) and 4 neon tetras. I’m going to get more neon tetras I just didn’t want to add too many at once. How can I help to stop fin nipping?