03-07-2003, 09:38 PM
It really depends on the location and type of fish. Generally fish in warmer waters are very difficult to age due to the lack of scale rings. Yet in colder waters, most of the trout species don't even have scale rings and therefore cannot be reliably aged. Perhaps the best info for a specific species or body of water will come from your State's department of wildlife. Get in contact with a fisheries biologist and they are more than likely to get you the information you would like.