I have kept glass shrimp, I think the Australian equivalent, in my tubs for a long time & there does not appear to be any negative impact on my animals, no gill nibbling like feeder fish do. The shrimp have been very good at tank cleaning as they feed on biofilm which grows on all surfaces of the aquaria & also if you miss the odd poop from your cleaning they appear to dispose of that too. They even breed in the tubs readily. They do leave little strands of poop on the clear bottom of the tubs but this usually gets siphoned up & the remaining is used by the plants. I have noticed a few shrimp sitting on the axolotls at times but they don't seem irritated or worried in the least. Actually I consider the shrimp a very important part of the bio systems of my tubs for keeping the water healthy & clean, this is only my opinion based on my observations.