Practical Fishkeeping has received complaints about films posted on the video sharing website YouTube which show fish and their prey being subjected to cruel acts.
Several videos show live mice and frogs being dropped into fish tanks while their owners film them swimming around and being attacked by large predatory fish.
Others show fish placed together apparently for the purposes of filming their fight.
One video shows a number of Oscars, Astronotus ocellatus, which have had body-piercing spikes inserted into the flesh on their lower jaws.
Dozens of clips posted by piranha owners show their fish being fed live prey.
In this clip, a live mouse is dropped into an aquarium, where it is then torn apart by a shoal of Red bellied piranhas.
Flag as inappropriateReaders Tom Messenger and Nicola Moir told Practical Fishkeeping Online: "It is, in our opinion not only cruel, but it puts a bad light on the fishkeeping hobby as a whole.
"There should be more action taken by websites such as YouTube to take these inappropriate videos off the site, and then ban the users who posted the videos in the first place.
"If cock fighting and dog fighting are not allowed to be shown on such sites, then why should these videos still be allowed? If you find one of these videos, please flag it as inappropriate."
YouTube's Community Guidelines indicate that users must not post videos showing dangerous or illegal acts, including animal abuse. It advises users to flag any videos breaching these guidelines as inappropriate.
YouTube says that each flagged video is promptly reviewed by YouTube administrators who work around the clock and will immediately remove any content that violates its Terms of Use.
A YouTube spokesman told Practical Fishkeeping that it was company policy not to comment on individual videos, but that it did not allow videos showing dangerous or illegal acts, as clearly indicated in its community guidelines:
"Our community controls the content, and they're the ones who flag the content they deem inappropriate.
"Once a video is flagged, YouTube reviews the material promptly and removes videos from the system if they violate our Terms of Use."