swim bladder?
 

I figure you guys will prolly know what this is. I always forget about it till I start cleaning some speckled trout. What is the white rubbery like sac that I hit with my filet knife when Im cleaning these fish? I dont really recall it on other fish that I clean. I know its some tough stuff though. Just curious.

your correct, i cut the belly out before i run the knife down the side, makes it easier

Why dont I see it in other fish?

don't start me lying

it IS a swim bladder
 

It is a swim bladder. It is used for holding air to suspend the fish at different levels within the water column. It acts somewhat like balast tanks do on ships. If I am not mistaken ALL fish have them, but it is just more pronounced in others. It will be more pronounced in species that do not particularly stay in one place in the water column. For instance redfish have their mouths pointing down as they are more of a bottom feeder. They primarily stay along the bottom of whichever water body they are in and therefore do not have as big of a need to be suspended at other areas within the water column and therefore have a smaller swim bladder. Trout tend to not occupy one particular area within the water column and are much more active feeders. They rely much more on a their swim bladder as they search out bait they try to stay suspended lower in the water column in hopes of being able to ambush it's food in the middle to upper layers of the water column. You can also tell that the trout use their swim bladder to actively feed this way by their body design with a pointy head and more slender build.

Sorry for any spelling errors. I just woke up and it's 3:30 am so I really don't care about them right now.

correction
 

Just did a lil research.....not ALL fish have the swim bladder. Some do not have one and others may lose it as they grow. Some fish that do not have them simply use their fins to suspend in the water column and others are more prone to being bottom feeders where it is not as much of a need to have a swim bladder....just an FYI.

Makes sense to me

Tuna do not have them...grouper, snapper etc. do

It's a good thread sealant like teflon.

:confused: never used fish bladders for that?? Might give it try LOL!