I'm not an expert but I don't think your pleco ate your mollies-they are not carnivorous, but they could have eaten the carcass. What is the size of your mollies? What are the other fish in the tank? I think one of them could have killed your mollies.

I've also heard of plecs eating other fish and becoming quite agressive. It is likely your plec, Lloyd, ate the mollies. Plecs are nocturnal so sleeping fish at night are easy prey for them, especially if the fish are small. The plecs will also "suck" other fishes slime coat off because it is a source of protein. This means that even if your fish are too big for Lloyd to swallow, he may be sucking their sides at night and leaving them vulnerable to other infections.

As they grow larger plecostamus become more agressive and more hungry than when they were small. If the algae source is low then they will turn to alternative sources of food. I would recommend feeding Lloyd those algae wafers before you go to bed (frequency depending on how fast he eats them)and hopefully he will keep off your other fish. I think the bristlenose plecs are what I've heard is best recommended for a community tank becuase they stay small and are more peaceful.

I have a large pleco, about 18 inches long, the tank if full of guppies, swordtails and mollies. He doesnt even eat the danged snails that came with the plants. Plecos are mostly herbivores, but I've had plecos before that did scale off large goldfish. A pleco will only resort to other fish if he is going hungry. Fill the tank with plants and if you decide to get more mollies, quarantine them before adding them. If I have fish die I usually find them either floating, tangled in the elodea or stuck to the power filter intake. Mine gets pond pellets and algae wafers. He is the one original inhabitant of my 65 gal tank, I bought him when i set that tank 5 years ago; that is his tank, anybody else is extra. When I got him he was a little over 2 inches long, now he is my pride and joy. They will eat carcasses on the bottom, thou, if your mollies just died and he found them...well, they were snack food.
Enid

Enid the best snail remover are loaches. Most types of loaches eat snails. I dont think it is much as being agressive as the size rule. Its just natural for any larger fish to eat smaller ones. A good example is most livebearers eat their young. While african cichlids an,agressive fish, are much better parents and protect their young. Thay carry the eggs in their mouths(some species). If you get a nice piece of driftwood and allow some algae to grow on it the pleco will probably never get off of it.

Mollies are probably dying of something else and pleco cleaning up the bodies. Don't mollies do better in a slightly brackish tank?

Plecos can kill big slow fish like sleeping goldfish, but they aren't going to catch healthy mollies.

Mollies do like brackish but most are kept as fresh. Adding some salt to the water can benefit them. As long as not to "salty" the plecos will be fine with it.

Hi i have a lady who breeds pleco and i got four off her and i have baby mollies in my tank and i asked her if they would eat them and she said no they will only eat eggs but i do have different. Fish in my tank and they have eaten my baby mollies before. But i have a pen for the mums to have them in the pleco have touch my mollies and some was born this morning

Sorry ment to put have not touched. My baby mollies

The right answers are the people that said if it fits in it's mouth, it will probably end up there. All over the internet everyone says Pleco's are docile and herbavore's and won't eat other fish, WRONG!!!! I had my Beta's from the time they were babies and my Pleco ate 2 of them. HEART BROKE!! When I asked the Petco Biologist about him eating all $150 of my plants he said, "watch him, because they can also harass all your other fish and reek havoc in a tank". I believed the hundreds of internet experts and kept him. Soon as he got big enough, he started munching my Beta girls. Not sick fish, not ill fish, not cuz he's hungry, He's just a big black brown spotted monster!!! Into the spare tank he goes until I can figure out what to do with him. I understand these communities are just sharing their experiences, but I'm pretty upset that even the online stores recommend them as docile, great for community tanks. Maybe a lot of people have gotton lucky, but if you love your fish like I love mine, I would stick to small suckers with medium fish because my girls are far bigger than guppies or Tetra's, they are full grown Crown Tail Beta's. First one was ate in the middle of the night, Second one was gulped while I was gone for 45 minutes in the middle of the day!! He didn't leave one little sign that Big Bertha ever inhabited the tank, just gone, poof! Like a thief in the night. Happy Thanksgiving, and Good Luck!! :)