I've had my Shrimp for just over a year (Tiger, blue pearl and 'yellow'). They live with a few small fish and all is usually well. Every now and again (maybe 2-3 times a year) they race like crazy around the tank. Ammonia is reading 'zero' but that's only with a basic test strip so a bit hit and miss and they are eating and breeding well - not all shrimp are racing but I would say the largest and oldest three or four - the rest are behaving normally.
Should I be worried (temperature is the same as always) - and if this is 'normal' why are they doing it?
Many thanks - still learning

Cheers - Louise