My red tail got its tail bitten off by a jaguar cichlid idk if the tail would grow back or not

[fishmonk]

Have you tested your water?

No

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?

21-30%

How frequently do you change your water?

Every month

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.

 

[Deadeye]

Welcome to the forum!
That damage looks pretty severe. When it’s all the way down to the bone like that, it generally will never heal. Furthermore, there is a high risk of infection and mortality associated with it. The best bet is to get the fish into a hospital tank with antibiotics running as soon as possible.

 

[quikv6]

I have had 2 fish have that have lost their tails completely. One was due to being stuck in a rock, and the other was a clean bite. Both fish were smaller than a red tail, but both fully recovered and grew a tail back.

What I did in both cases was a hospital tank with a 50 percent water change daily. I added salt to the tank. I also did a methylene blue dip for about 30 seconds, twice daily for the first few days. After that, I just left it up to clean water, salt, and a completely stress free environment. I kept light off the hospital tank as well.

Fish can be very resilient, but you have to give them the best environment you can to support a potential recovery.