The Blennies are the life and soul of the tank. They’re the most active, the most visible, the most entertaining creatures in there. I started with just the one, but now have five in there and they’ve thrived. When there was just the one, it was a little cautious for the first week or two but as soon as I added a second and third, the behaviour changed and suddenly it was much more active.
The first one I put in (who we named “Ronnie”) is the largest and seems to be the top dog. He does what he wants and the others fall in line. They’ll eat whatever food I put in and very quickly learned to identify that the turkey baster entering the tank meant it was food time, and they’ll happily take turns to chug from the baster. Of course Ronnie usually eats first, but the others aren’t far behind. Everything else has to pick up whatever scraps the Blennies miss.
So far they haven’t been aggressive with anything else in the tank other than the Brown Shrimp which turned them into rabid Piranhas. They’ve never reacted like that with anything else, but as soon as the Brown Shrimp went in, the Blennies tore them to pieces. Lesson learned. No more Brown Shrimp in the tank.
“Ronnie” has grown increasingly aggressive with food and if I put in a frozen shrimp or piece of mussel the Blennies will quickly swoop in and there’s a feeding frenzy. They’ll fight the crabs and anemones for the food so I try to feed everything separately when possible.
The Blennies live peacefully with the various Goby species in the tank and they have shown no aggression to the Common Prawns in there, even the smaller ones. The Brown Shrimps though? Carnage.
I did come down one morning to find “Ronnie” flying around the tank with the Hermit Crab in his mouth, but I’m certain that the Hermit was already dead before he got it. The Hermit hadn’t been moving around much for a few days and I’d been concerned about it, so I don’t think it was killed by the Blenny. It had been in there for a couple of months without there being any kind of incident, so I think it was just opportunism rather than murder.
In terms of their behaviour, I expected them to hide a lot more than they do. They will spend some time hiding in the rocks but never for long and they’re usually swimming around the tank investigating. They’re pretty fearless too. If I move the algae magnet to clean the glass, the Gobies will scarper immediately where the Blennies will come to investigate. This is probably why they were so easy to catch in the first place.
Most of them were caught by just swishing the net into seaweed, but I also got one in a fish trap baited with frozen prawns.
