Here are a few more notes about your pond's deep water zone (volume below the thermocline) that were not in the Feburary "structure question" posts.
As your thermocline forms in Spring the water below the thermocline usually contains ample dissolved oxygen. Fish can be in deep water then, but most will probably prefer the warmer surface waters. But as spring progresses oxygen is gradually depleated to levels where fish can not "breathe" any more; thus they all have to move up to the warmer top layer. LMbass and other "warmwater" fish are more "comfortable" in this warmer water anyway. Warmer is better for them, they "feel" better and grow better in warmer water until it gets above 92F. Then things get a little too hot. Anyway, after several weeks of oxygen depletion, oxygen is all gone from the zone below the thermocline. When oxygen is depleated from the deep zone if you don't get out you suffocate and die. This includes all bottom invertebrates clams, crayfish, sediment worms, insect larvae, etc. The deep area is now a "dead zone".
Since it is now late in the summer season, your thermocline will be located about as deep as you will normally see it, year after year. Below this depth do not expect to find fish at this depth or deeper because there will be no oxygen in the water for them; especially in a typical TX pond. Oxygen will return to the deep water for the winter, early spring seasons during the fall/early winter turnover.
Exceptions: Rarely, in some clear-water, very low productivity, deep lakes some oxygen remains in the water below the thermocline by late summer. You can recognize these lakes because they support year-round trout populations. This type lake occurs most frequently in northern states and Canada but a few occur in the south.
