Guppy's Tail Looking Eaten

[HarpyFishLover]

Hey helpful fish members,

I have yet another issue to bring to you. (It really is a blessing you have you guys as a quick option in case of emergencies...) So I have this really beautiful male guppy. He has this giant, pink tail with grey dots on the end. A few days ago, I noticed his tail seemed smaller. Then, the day after, I saw jagged edges- the spots were gone! It looks like the end of his tail has been bitten right off. This is a 10 gallon, he has two other male guppies as well as two (yes, I need more, getting them later today) harlequin rasboras for tankmates, and I have hard water- about 250 ppm.

pH is 7.7
Already given GH...
Ammonia is always 0
Nitrite is usually 0-4
Nitrate is around 10

I have two real plants (not quite sure what one is, but the other one is Anubias Nana.) and four plastic, as well as a plastic bonsai tree.

I'm wondering if it is the tank bully biting him, or the plants? Also, do I need to put Melafix in there, or any other meds?

 

[NickAu]

Male Guppies can be aggressive towards each other, I once had 10 male Guppies in a 20 gal, I found a nice male and decided he would look nice in my tank, so I got him, a few hours after I introduced him to the tank the dominant male ( he was a bully towards all the others also ) took a chunk out of his back and kept attacking him, I ended up pulling the injured fish out and putting it to sleep as it was badly hurt.

 

[ginaekdal]

This will likely be identical to the situation you posted about previously with your other fish and the advice given there both about the guppies, and the rasboras in terms of water and tank size, still stands.
 
You should not be seeing Nitrite in a cycled tank.
 

 

[HarpyFishLover]

About nitrites. I checked after posting that and found 0 nitrites. That was a guess. I was also thinking of nitrates, which I do have some of.

 

[HarpyFishLover]

Well... not sure what to do. This tank looks beautiful, but the fish are pretty vicious.

On the issue of Max biting Sammy, I found Sammy facing off Max in a very angry matter. I'm like "GOOOO, SAMMY!"