Once the Hydrilla comes to the top and forms a mat does it thin out under it? Or does it stay dense from top to bottom?

Keven

Here in my area it doesn't float like a mat if that's what you are asking. Here it is extremely thick on the bottom and thinner on top. I usually punch through with a 1oz or bigger Tungsten flippin' weight and a soft plastic t-rigged lure.

What you will find under the matted Hydrilla is tunnels, caverns, & caves  

On Guntersville when it gets all nice and scummy up on top, some of the stuff undereath it dies off leaving a lot of room for the fish to roam around. That signals the start of the frog bite. Not all of the grass gets that high though.

Catt, don't forget bass.  Big Mean Bass   ;D

So it would probably be beneficial to use some type of rattle on a jig or plastic to help them locate the bait.

The hydrilla that I have fished is either just short, water level 'stalks' or the stuff on steroids... the kind of stuff that grows in very very long strands. I think this is the stuff that creates mats (first) or floating islands (second). From what I have seen, when it is the short stuff it is generally pretty thick and I found the thinner areas (holes, pockets, edges) to fish. When it starts to mat or float away from shore I then 'punched' through to the darker (and cooler) water underneath. I never bothered with any rattles or other noise makers... those fish are in ambush mode under there. I am gonna say that again... those fish are in ambush mode under there... stay focused between strikes (sometimes the strikes are few and far between) or you will miss fish or lose equipment! Some of the most violent strikes I ever had came from fish under hydrilla mats.

Hydrilla is a submersed plant, meaning it is attached to the bottom of the body of water and does not float around.

Hydrilla is a submersed plant, meaning it is attached to the bottom of the body of water and does not float around.

That is not always true. I have personally seen "floating islands' move from week to week on Kissimmee and West Lake Toho. I am quite sure it happens elsewhere too.

The plant is submersed, except when branches have reached and grown across the water surface; sometimes found as detached floating mats.

http://aquat1.ifas.ufl.edu/node/183

Here in my area it doesn't float like a mat if that's what you are asking. Here it is extremely thick on the bottom and thinner on top. I usually punch through with a 1oz or bigger Tungsten flippin' weight and a soft plastic t-rigged lure.

Amen brother.

I fish here in Florida, and seen different lakes with Hydrilla Matted so thick you couldn't,t PUNCH at all.Pretty much had to fish around them.It will grow and lay on the surface giving a false look like floating mats.And yes it stays as thick as the patch you have found on top as well as the bottom.