so i had this same question a little over a month back regarding an independent study/research regarding axolotls. Mine did not become reality unfortunately due to my school schedule and preparing for SATs etc. So here are some of the ideas i was thinking about:
1) buy an egg, hatch it and record its growth and behavior change in a very detailed report everyday till adult size has been reached (i assume you are in a time crunch so you could present the first month of your data then continue your research on your own if you want)
2) Get two juveniles (about 2-3 inches in size but from the same batch) and feed one of them pellets and the other wither chopped up earthworms or other sort of live edible organism thts a good staple diet. Since both pellets and earthworms are considered to be a safe and good source of staple diet in the axolotl community I doubt you would harm one over the other. With this study you could record if there is any change in the rate at which they grow etc. if there is no change between the two lotls rate of growth then you can for a fact say that according to your study both pellets and earthworms are a good source of food for axolotls. Keep in mind genetics play into this as well so scientifically it might not be a super reliable study, yet it could be fun.
3) conditioning/ teaching tricks to your axolotl. so this might fail depending on your axolotl, I have seen some smart on the ball axolotls and some sorta dumb ones. But if people can teach goldfish to go through hoops why not try that on axolotls. I would research how teaching this to goldfish is done then implement that technique or a similar one on your axy. This could be pretty cool if it works and for the science part of it you can connect it to pyschology and conditioning and how if there is a reward in the end the success rate it much higher etc.
4) Depending on how many axolotl you own, you could test the effect of isolation on behavior and eating habits (axolotls being the little water cows tht they are i doubt it will have an effect on eating). It might actually affect habits especially if you isolate an axolotl that has been living in the same tank as another axolotl(s) for a while. Study the habits in a group, isolate, then restudy the habits alone, compare and contrast.
these are the ones i can remember off the top of my head. Also keep in mind the data will not be scientifically accurate at all because you are doing this on a few axolotls. For it to be considered "accurate" or "proven" you would have to test in on thousands of axolotls which i imagine is not too practical. but if its just for a highschool/middleschool science fair it might be fun to try one of these. Basically you would have to do some sort of a behavioral/observational study.
I personally find axolotls and my other pets (goldfish and turtles) so very fascinating. If i have free time ill just sit in front of their tanks and watch them and see wht they do through out a period of time. You can be surprised on how many habits of your animals you pick up on just by watching and not even moving.
good luck on your project!! You should definitely post about your final project, i would love to take a peak at it
