I went Fishing yesterday and caught quite a few bass that had a yellow stain on their bellies. It was the color of pee. Are these male bass that has been fertilizing eggs?

A lot of times bass male and female will get some discoloration on their stomachs from maintaining the nest. While they are clearing a spot some of the sediment they are clearing will stick to them. Don’t know if that is the case where you are that's just my .002.

Jay

I've seen "yellow" bass in two circumstances:

 

-Winter/early spring when bass are in/recently come out of winter quarters where it appears they are lying belly to the bottom (as these fish often have mud/clay on their bellies).

 

-During summer when they are in shallow densely vegetated slop bays.

 

I also see "golden-copper" individuals here, so far always from deeper water. Dunno why. Very curious.

I see this in the dead of summer from shallow weed dwellers:

 

I see a lot of this in cowardly fish.

I've seen "yellow" bass in two circumstances:

 

-During summer when they are in shallow densely vegetated slop bays.

 

The bass from my lake have yellow bellies year round. The lake has heavy vegetation and very mucky bottom. So to the OP, this is probably the case.

I see this in the dead of summer from shallow weed dwellers:

 

Wake that kid up and stick a rod in his hands!

The entire belly region was not yellow. Bad explanation.

It was only from anus or vent to the tail. It looked more like a pee stain than anything.

Maybe I scared it out of them.

trailer-----haha!  that's what i was thinking with the topic's title!

I caught a smaller one in between some vegetation and the shore. It was very yellow. And stunk...

I called it a swamp bass

I caught this girl today. Is this what you're talking about? I'm curious as well.

That's a nice Spot sbfishySC.  Hartwell, or Keowee? 

I caught this girl today. Is this what you're talking about? I'm curious as well.

Yes

That's a nice Spot sbfishySC.  Hartwell, or Keowee? 

 

Keowee

Just variations in color. I've caught many fish early in the year that are brilliant white and the next is lemon yellow on the belly. I was once told that crawfish eaters tend to be more yellow than their counterparts that eat more baitfish. I don't know that I subscribe to that theory exactly, but I'm sure diet can play a part in coloration, too.