Stocked fish and parr marks.

[gfen]

Do stocked fish exhibit parr marks?

If not, why not?

Would a stocked fingerling, or small enough fish, develop them if no stocked fish do?

I picked up rainbow today in a place where I know they don't reproduce on which fading, but present, parr marks. I was under the impression that stockies don't develop them, so my whole world's been turned over.

'Splain how!

 

[tomgamber]

All juvenile salmonids exibit parr marks. After the fry absorb the yolk sac, they begin feeding on plankton. As the fish grow , they develop parr marks on their sides. At this stage, the fish are called parr. Rainbow trout lose their parr marks as they mature. We associate parr marks with wild fish because most trout when stocked have already lost them so if we see a fish with them we assume it must have been bred in the stream. Fingerlings that are stocked could be in either a stage of still having parr marks or already having lost them. Most, I assume,would still have them. That's my story and I'm sticking to it.

 

[pcray1231]

Yes, stocked fish have parr marks.

All trout have them when young, and lose them at a certain maturity level. Obviously maturity has something to do with age, but its not just age, its heredity, size, diet, etc. Most of our adult stocked trout have lost or largely faded their parr marks before they are stocked. Fingerlings still have them, and even the smaller adults often show some parr mark remnants. Likewise, large wild fish often don't have them.

 

[gfen]

Fair enough, at some point it had entered my memory that stocked fish didn't exhibit parr marks, and I never bothered to compute on it any further.

I just had the assumption it had to do with diet (and a lack of key vitamins/etc in the trout kibble), but figured I'd ask.

 

[Fishidiot]

What Tom and Pcray said.