Jimmy,

Join the club on hot and dry and increased algae. Here in northern Indiana both are going hand and hand. Some natural lakes here that never have algae blooms or filamentous algae have them.
I also have had more filamentous algae on one of my ponds than normal. I believe the increased sunlight of drought conditions is contributing.

The fish species you are eluding to are Grass Carp. Even though they are very effective on some aquatic vegetation, all the literature I have seen is they will probably ignore you cattails although they may eat some of the new tender shoots.

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.