I have 5 yellow neocardinia in this small UNS 45 cm tank. They scoot around a lot in a stressed way. It's happening too constantly to be mating behaviour, though the female was carrying eggs. I can easily move them to another larger tank, although it has reds so I'm a bit concerned about cross breeding. I accept if the tank feels too small for them, but I'm a little surprised. I'd kept them very happily in a 35 cm 30 litre tank before, though maybe the depth of that helped. The TDS is 160 ppm and all the parameters are fine, no ammonia, nitrates low, PH 6.5, plenty to browse on, lots of floating plants, leaves, regular courgette feeds (which they ignore). I could put some of the baby reds in there instead? This is barely a question, as I am accepting their behaviour is a clear indication. But I think other people here have shrimps in similar small tanks, so I was just curious. It's a shame to have nothing but snails in the tank, which generally I am happy with, modest as it is.