Tiny but mighty creatures
Imagine a monster with many tentacles, bulging eyes, antennae, and a pointed mouth with thousands of tiny teeth. Imagine that it reproduces quickly, so thousands of other identical monsters always surround it. You don’t have to picture it because this exists. Fortunately, though, it isn’t as large as you may believe.
These are microscopic sea parasites. These unpleasant crawlies vary greatly in size, but they may be difficult to detect with the naked eye. That is not to say that they are harmless. As parasites do, they enter the bodies of fish and feed on them, as well as potentially killing them.