Worth noting that there is a much different take on the feeding of live fish in the UK (see the below statement from DEFRA). Almost all of the British keepers I've spoken to have been scandalized by how prevalent the practice is here.
"1.6 Live feeding of vertebrate prey is to be discouraged (see Section 5). Although the Animal Welfare Act 2006 does not prohibit the feeding of animals with live prey, the live feeding of vertebrate prey should be avoided save under exceptional circumstances, and only under veterinary advice. Where it has to be undertaken, a written justification and ethical review process must have been undertaken and agreed by senior staff weighing up the welfare of predator and prey; feeding must be observed and live prey not left in the enclosure. Such feeding should not take place in the presence of the public"
https://assets.publishing.service.g...data/file/69596/standards-of-zoo-practice.pdf