Anemone and clownfish

5/14/04
I went to the fish store on Thursday after work, ready to bring home my clown pair and their anemone host. Since we’re going to be away Saturday, I wanted to have Friday to observe them and make sure things were ok. On the whole, I was feeling pretty good about the tank--things seemed to be healthy and stable and I felt ready for the next challenge. When I got there I told the dealer about the death of the bicolor blenny. This hadn’t worried me all that much, since I’d been blaming it on the feather duster incident. But it worried the dealer a lot. She didn’t buy the feather duster being the cause, and since bicolor blennies are generally hardy fish, she wondered if I had something going on in the water--pathogen, trace amounts of some contaminant, whatever. But the fact the firefish goby is still alive was a good sign, since they are generally prone to die off easily. It was ironic that the one time I wasn’t worried, the dealer was, which of course made me worry, too. But in the end, we decided I would take the plunge.

Let me introduce you to the new citizens. These clownfish don’t look quite like Nemo, as they are not the Amphiprion percula species but rather Amphiprion akindynos, hailing from the waters off Australia (although mine were captive bred). They have a white tail now, but they are youngsters, and will lose that as they age. Of course you don’t have to provide an anemone for clownfish, but I wanted to, despite the fact anemone are very difficult. The easiest type of anemone is the one I bought, so called bubble-tip anemone. An anemone is basically a sack around a gut. There is an easily visible mouth, into which food goes in and anything indigestible comes out (about a day later). They feel rather slimy, as they create a lot of mucus, and of course the tentacles sting as a protective measure (not noticeable by most humans, although some people are sensitive).

The first tricky thing is to place the anemone somewhere that it will be happy. If it is not happy, it will wander, albeit very slowly, in the only way it can, by contracting the muscles that form the sack shape. It wants its base to feel secure against a rock, ideally on all sides. But sometimes they back into an opening in the rock too far and then don’t get light and die (as you perhaps guessed, there is no brain). I did my best to place it in a good spot, and the thing was maybe the size of a tennis ball, all contracted, when I went to bed. The clownfish were not happy that it wouldn’t open, as the Coral Beauty was chasing them and they wanted the protection of the tentacles. They tried hovering among the anthelia branches on the other side of the tank, but that species has no stinging ability and really isn’t big enough to offer them shelter.

In the morning when I got up, the anemone was BIG. The diameter of the tentacle disk was maybe 6-7,” all floppy, and the animal had moved a few inches from where I put it. Later in the day it worked its way into a gap in the rock, so I had to push it out a bit and pull the rocks closer together. I think it is going to stay put now, but tomorrow will be the test. This evening I tried feeding it. You are supposed to get the food right on the mouth, but since the disk was vertical, the food rolled down. The anemone rolled up the lower part of the disk to catch it, and was slowly working the stuff toward the mouth, when along came one of the clownfish and helped herself to the anemone’s dinner. Apparently their mutually beneficial relationship does not extend to sharing food!

I’m sure I’ll get better at this. Here's a picture of the Caulastrea coral (left) with a single polyp in the middle that blew up like a balloon an hour or so after it got a direct hit of a substantial amount of food. The lights were out and I was using the flash, but if you look carefully you’ll see that one polyp is much bigger than the rest. BTW, the dealer said this coral is a colony of individuals, it is not a single organism, so the fat polyp got it all--that meal was not shared with the rest of the beast.