I discovered that the mod does not appear to be working on a server I play on and was actually crashing me whenever I would be able to see the axolotls in a bucket. Testing further in singleplayer showed that the mod did not appear to be working at all but did not crash in singleplayer.
I noticed that the version changelogs mentioned something about crashing related to dedicated servers, and that there was only one issue pointed out on the github so I felt like this likely hadn't been brought to your attention yet.