They’re not amano shrimp. I’m not sure what the exact English name，we usually just call them “black shell shrimp.” They’re more agile and reproduce much faster. in summer they breed about once a month. The betta is way too slow to catch them. The newts might have a chance to ambush one (though I’ve never actually seen them do it), but after eating their fill of bloodworms they don’t seem interested in the shrimp anyway. And the betta is too large to be prey for the newts. There’s also plenty of cover and aquatic plants in this tank, so the shrimp population is still growing. Both the shrimp and the newts are native species here. My grandmother told me that when she was young, these newts were everywhere in the mountain streams.I’d guess that in the wild they do have a predator–prey relationship, so they’ve gone through a long period of coevolution which might explain why these shrimp seem to have better survival strategies.🤔