measuring fish length

Oh, oh!!! I know this one!!!

Standard length is when you measure from the tip of the nose to basically the beginning of the tail (body length).

Total length is when you measure from the nose to the end of the tail. I think this method is the most commonly used.

You may see standard length or "fork length" (length to the base of the fork in the tail) used for some game fish.

(Demonstrating my Fisheries knowledge, and that I deserved better than a B+ in that class... growl.)
 
Standard Length is the more professional measurement. Tail fins are notoriously erodable.

Since you don't want to subject your fish to unnecessary net-handling, and you aren't measuring a thousand fish, lay a plastic ruler in the tank, get some milk and a plate of Oreos, and wait for him to measure himself!
 
I use either the SL or TL method, depending on the fish. If it's got a relatively short tail or where there's not a really clear stop to the body and start on the tail I measure everything. Something like a fantail goldfish or betta, with REALLY long or feathery fins gets body-measurement only.

Usually I just eyeball the measurements (grew up in a household full of tailors, so I think I've got measuring tape lines permanently seared into my field of vision....) and round up to the 1/2".
 
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