I doubt very much that the species mentioned above are predominantly bottom feeders.

Carp and Bream you'll get at more or less any depth in the water column, Tench less so, but it's not unheard of to get them off the bottom.

The more I think about the ways in which these species feed, the more I'm inclined to think that it may a be a swim bladder issue. Feeding Bream, Tench and Carp often give themselves away when in a feeding frenzy with gaseous bubbles of different sizes. Maybe some of this gets trapped and rolling equalises the pressure making them able to return to the bottom and carry on feeding on a bed of bait???

Catching fish off the bottom is less likely to have so much an effect as it'll be more of a opportunistic meal.

All of the above is subject to matters of opinion I guess?

Well, I would have to say I have caught very few bream ( of any size at all) off the bottom. No tench at all, and my carp have more or less all been on the surface or the bottom. But having said that, I don't often fish midwater in stillwaters.

As for pressure equalization: the pressure in water changes much, much more rapidly than in air. A depth of 10 feet of so will equate ( approximately) to a 5 psi increase in pressure, from that measured at the surface. ( an extra 1/3 over ground level air pressure) So, because a rolling fish would be equalisiing pressure at the surface pressure, it would not equip him for feeding on the bottom. He would be out by 5 psi in 10 feet of water, quite a lot. If the roll enabled the fish to open and equalise swim bladder pressure at the surface, he would not then have neutral buoyancy back at the bottom. So I discount any equalisation theories.

maybe its just something simple like a gulp of air to help digest the food content, like ducks take a mouthfull of water when eating bread to help break it down, or to give the gills an airing maybe, next one I catch Ill ask , but it may be a while

In my experience when I see rolling fish and cast to them I often get a take. I feel that rolling fish can be caused by several things. When fish have a lice infestation they often hit the surface or roll to try and knock them off.

I mainly believe that fish that are rolling are feeding fish that are feeding avidly and in doing so are picking up muck and debris so hitting the surface is a way of clearing out their gills.

Only a theory - I am good at theories - good at practice? Hmmmm.

Martin.

So they can laugh at us idiots.