Like the goldfish/dolphins in sea they become curious of you and will start following you, apparantly. If you're a smn with summons out, beware. Once this thing aggros and follows you, your summons will take it as a threat and attack.
If its like the fish in sea, you should be able to para, blind, and use other enfeebles on it without it attacking. Once you deal any sort of damage to it, though, it will attack you.