guppy with damaged tail

[KittenFishMom]

On day 5 of my QT tank, I noticed a chunk missing from one of my guppy's tail. I am wondering if it is fin rot or a case of nipping. There is a native barred killifish and a male betta in the tank, either might have nipped. I also lost a guppy the first night of QT with a damaged tail that I thought was fin rot. I will try to get a photo, but so far I haven't been able to get a good shot.  The piece that is missing from the tail is rectangular and goes back to the fishes body with tail fin above and below the missing chunk.  The tail was in excellent shape on day 4 of QT.

Do you think it is fin rot or nipping?

If it is fin rot, should I do the full ich-x & antibioitic a second time? Maybe adding the paraclense, or holding off on the paracleanse for another week?

If it is nipping, which fish  do you think it might be and how do you recommend isolating the fish for the rest of the QT? (I will have a second week of QT for Paracleanse after this week of ich-x and  the antibiotic that starts with "M".

Thanks for all your years of wisdom

[Gator]

The Killifish is probably the culprit doing the nipping. Happy Holidays.

[Beardedbillygoat1975]

I would say the chances of either the killi or betta nipping him is near 100%. I would start with some aquarium salt for a few days and see how it goes. They heal quick typically. I would not jump to meds too quickly. In terms of isolation if you have a tank handy it would not hurt to make sure he's not stressed, eating well and has time to heal. I would treat the other 2 with the med trio and wait a few days of salt, food and healing before hitting the guppy with the med trio. 

[KittenFishMom]

@Beardedbillygoat1975 I had thought I got all the minnows/ shiners out of the tank before QT, but the killifish managed to stay in the tank. I added 3 male endler, 3 male guppies (lost one the first night) a corydora and a male betta.  Because the betta was very stressed and the guppy did not look so good, I did 2 or the 3 trio meds. Those meds are still in the tank with the fish.  I could buy or make a breeder box for the killifish or for the guppies to keep them safe in the tank.  Should I add salt in addition to the meds? I have plants and scuds in the tank, and it is cycled. I still need to do a week of paracleanse the new fish.

[Beardedbillygoat1975]

Stay at a dose of salt around 1 tablespoon per 5 gallons and you'll be fine. The plants and scuds should not be too hard hit by the salt. We are just trying to create optimal conditions for healing and lower stress. Guppies like the water hard and full of minerals, salt provides some of that. Also guppy breeders are notorious for salting their water. 

[KittenFishMom]

Update: I decided to put the killer killifish in with the rest in the 55 gallon tank and treat the 55 gallon tank with the quarantine trio. Anyone know if I should use 5 or 6 packets for a 55 gallon tank?

Update: I watched Cory's video and caught the killifish. He is now in the net which is across the top of the tank, hanging well into the water. He isn't happy, but he isn't able to bit anyone.   Now to figure out a cage that will hold him while letting the water through for the next week of QT.

Original post:  The guppy with the damaged tail lost the rest of it's tail today and died. I am trying to catch the killifish, but he is very fast and lived most of his life in the lake with fish trying to eat him. He has great avoidance skills. I might try baiting a net with bloodworms to see if he will swim into a still net. I am not sure where to put him once I catch him. I need to see if I can sew up a breeding box with netting and drinking straws.

All ideas on catching the barred killifish or building a holding cage for him are welcome.

Edited December 24, 2021 by KittenFishMom