Pleco killed frog

so my friend has had a bristlenose pleco for 4 years. I am 99% sure it is a girl but it is named tod. he had an ADF in the same tank and he said there was algae or bacteria on the ADFs back. and so tod latched on to the ADFs back and killed him by sucking through his skin on his back. ideas on why the pleco did this?

 

Often times when certain pleco species don’t get their necessary protein intake they can/will attack tank mates. I’ve never had BN do it but commons and chinese algae eaters do it as do other carnivorous “algae” eaters.

There’s also the chance that the frog was already dead, plecos are scavengers so they will readily go after dead tank mates.

 

my friend said the frog was alive and the pleco was attached to it weeks before it killed it

 

Your friend should of separated them soon as they saw what was happening, but I guess lesson learned the hard way.

 

he told me they were named after characters in a movie and tod was the good guy and the ADF was the bad guy and in the movie tod killed the other guy so he should have seen it coming