While cleaning a white bass I found something with the organs. It was hard and solid, and I don't know what it is. I've never seen this before. Anyone have any explanations?

Would you be able to post another photo of this object with something of known size next to it, like a coin?

Also, did you find one or two egg sacks or milt sacks inside?

My guess is that this is a shriveled, atrophied ovary or milt sack.

Neat find. Thanks for posting!

I was not able to use an object for size reference. I got rid of this already. This was a 15-16 inch fish, and this thing seems to be proportionally sized like the rest of its guts. There was also 2 egg or milt sacks (yellow fatty things) inside as well.

Well, the "yellow fatty things" sound like the normal egg sack. There goes that theory ... don't know what else to suggest.

Any time I run into something odd on or in a fish, I will not eat it. I have seen some sort of black flake looking stuff in the meat and I wouldn't eat it. Only seen this a few times in 50 plus years cleaning whites, still don't know what it was.