Rogue axie - what to do?

About 3 months ago one of my axies (Ernie) attacked his slightly smaller tankmate (Eric) and as a result Eric lost an arm. I separated Ernie in a tub and let Eric heal for a month or so, then bought a much larger tank.

I reintroduced both axies to the new tank and they got along really well until recently. Eric's arm has been growing back with great progress. However, a few weeks back I noticed Ernie had taken nips out of Eric's tail fluke. And tonight I noticed Eric hiding in his cave ... when I coaxed him out, I saw his whole (new) arm was a bloody pulp.

It seems Ernie just can't help but attack Eric. I've upped their diets about two weeks back so they're both eating one large mealworm a day, but it hasn't had an effect. I've got Ernie in a separate tub again.

I don't really want to have to get rid of Ernie, but it seems like the only solution. And I don't really want to divide the tank. If anyone has a solution out there, I'd be glad to hear it. Otherwise I think I have to let Ernie go, and I've had him for 3 years, so it'd be a shame.

Mealworms are not the best food for axies, earthworms or pellets are best. It could be that they are hungry enough to bite each other.

Are they the same size? If one is smaller than the other it's not unusual for the bigger one to go for the smaller one.

Separating them until the wounded arm is healed is a good idea. A divider may be a reasonable compromise if you're just waiting for one to grow a bit.

Thanks for the quick reply. I've isolated Ernie and my plan is to keep him in this separate tub for a few months, until Eric's arm regrows (third time lucky, huh?).

I'll feed him earthworms, and perhaps twice a day, checking that he isn't getting obese. Eric is marginally smaller than him, but that's due to Ernie taking the end off his tail a few times! So really, they're pretty much the same age (3) and length (20cms).

After some solitary, a better/heavier diet and some time for Eric to recuperate, I'll reintroduce Ernie to the tank. But it's his last chance. I'd be gutted to rehome him as, despite his fierceness, he has been my pet for years. But if he persists in aggression, I reckon it's off to another tank for him.

I dont know how big your current tank is but yes an upgrade usually should be a first step, the more room they have to themselves the better. Separation can be a permanent solution because eric has been attacked by the same axolotl multiple times now, i would recommand not "trying to have them get along" again just because it wasnt once or twice but 3 times. Thats not fair to Eric. Also separation would allow you to keep both axies and keep them safely, i bought a tank divider a while back when I had my axolotl in with someone elses, watched their behavior very carefully and only then let them fool around on small intervals. when those went well i permanently removed it and they seemed to do ok and never had a problem. If the aggression continues you can keep in the divider permanently as long as your tank is on the larger end.

One other thing as auntiejude already mentioned is the meal worms as a diet. when i first got my axolotl i confused meal worms and earthworms together and fed mine small meal worms. Soon enough mine started to throw up her meals all over the tank because axolotls cannot digest that hard outer shell made out of Chitin. This can be dangerous but it also might explain ernie's hunger/aggression. Meal worms are also not very fulfilling i would think, earthworms always seem a bit more meaty.

I would say start feeding both of them earthworms or soft sinking pellets as auntiejude mentioned. If ernie seems that hungry maybe feed him 2 medium-large earthworms a day for 2-3 days then switch back down to 1 large earthworm a day. or pellets, I always found it hard to decide how much pellet food to feed so i stick with the earthworms. You can also go with your gut, axolotls in my experience do refuse too much food. I leave mine in a food dish and if it was not eaten within 2 hours then it was probably too much.

When eric is fully healed try the tank divider thing. I still think u probably should not put them back together since this is the 3rd attack, but ultimately its your choice and if you will do so please first watch them very carefully, maybe allow 10 minutes of very closely supervised "play time" and at ANY sign of aggression split them up. At this point they should both be fed real well with earthworms/pellet so hopefully the hunger factor will be out and you will be able to tell whether is Ernie attacking eric because he was indeed hungry, or because he is for some reason aggressive towards him.

one last thing, im not sure how many hiding spot you have in your tank but there should be atleast one per axolotl, in cases of tank mate attacks i would say more is better but that depends on the size of your tank. You dont want to crowd their swimmy/walkie area too much. If you have like a 40 gallon or so you could probably easily put 4 different size and shape hiding spots.

Best of luck to all 3 of you! Hope the problem can be solved

The mealworms I feed them aren't regular - they're from a breeder in Queensland, they're medium giants, about 5cm long and very fleshy, with only a thin chitinous shell. They also don't pupate, which is great. But yes, I'm going to vary their diet with some earthworms too.

I'll get another log or cave for hiding in i think. There are plenty of big plants and rocks in the tank, but only one log for concealment.

Thanks again for all the advice.