Fish and Game isn't taking any chances over a potential disease plaguing mid-Canterbury's high country trout population.
Several lakes are in lock down while samples of the odd rash, found on the fish's underbellies, are being tested by the Ministry for Primary Industries.
Fish and Game's Martin Taylor says anglers are supporting the closures.
"They just want to make sure everything's safe, everything's clean in terms of their gear. Nobody is flouting the ban."
Anglers are being urged to steer clear of lakes Lakes Grassmere, Sarah, Hawdon, Marymere, Pearson and Lyndon.
Mr Taylor says they can't take any chances with the fragile ecosystem.
"Worst-case scenario, there could be a serious fish disease. What we've got to do is take a really precautionary approach - suspect the worst, and then hope... there will be an answer that is not a serious fish disease.
"We're just not sure."
Mr Taylor says MPI should have results from sampling within the next few weeks.