Here you can find glitches that have been found in the game.

"White" Red Hawkfish

This glitch is triggered when you visit a friend, after you leave your friend's reef, your Red Hawkfish's markings will be white instead of red.
White Red Hawkfish Glitch 1
White Red Hawkfish Glitch 2

Clown Triggerfish "Twins"

This glitch is triggered the same way the Red Hawkfish glitch is triggered. When it's triggered, your Popeye Fish will be replaced by a second Clown Triggerfish.
Triggerfish Twins Glitch 1
Triggerfish Twins Glitch 2

Tubipora Coral Glitch

This glitch is also triggered by visiting a friend. Once triggered, your Tubipora Coral will be in the shape of a Sea Pen Coral.