Depends what you mean by health check, and what you would do if you detected a problem.
Most official health checks are carried out to allow fish to be consented to be transferred to another water. For this a sub-sample of 30 need to be killed. If you found, for example, a notifiable parasite, then you wouldn't be able to move any fish out of that water (unless the destination water also had the parasite).
Just keeping an eye on the fish that get caught is often a good enough guide to how well they are growing, if water quality is OK, if parasites are a problem etc. etc.