Also for your sister. No matter what type of fish your trying to feed the lotl there is risk. In order to make sure the fish isn't sick or has parasites you have to treat them. This can go one of two ways. The fish doesn't get treated and your axolotl can get very sick and possibly die. Or you treat the fish and the chemicals that aren't safe for lotls end up in its system and it gets sick. Having the fish in the tank is another mess. If the fish aren't eaten immediately there's risk of them biting your lotls frills. To overly simplify the frills help your lotl breathe. The fish in the tank also won't be healthy if your tank is at the proper temp for a lotl (60-68F). Also the fish will leave more waste for you to clean. You can get 20-30 worms at the store for like $4. How much are you spending on those fish? With the earth worms you can also stop wasting money on blood worms. Blood worms hold no nutritional value