#74: Our Reef Residents - Mero the warsaw grouper

One of my favorite reef residents in the GOT is Mero, our warsaw grouper, Epinephelus nigritus. In the 40 years that the GOT has housed fish, this is the only representative of this species to have lived here.

According to fishbase.org, warsaws can reach a length of 230 cm or over 7.5 feet. In our tank, this individual seems to be a slow growing fish. Although we have hosted this fish in the GOT since 1993, it is only about 3 feet long. In comparison, the other large Caribbean grouper species that we have here at the Aquarium, the goliath grouper, seems to grow much faster. It can be found in our Blue Hole exhibit.

Mero loves to eat tiny silversides!

Mero is interesting because he came to us as a Gulf Stream orphan (GSO) at least 18 years ago. Gulf Stream orphans ride the Gulf Stream north from the tropics to New England while still in their microscopic egg or larval stages. At some point they drop out of the stream close to shore and grow into miniature tropical fishes. We start seeing them up north in August. Since these tiny tropical fishes can't swim all the way back down south, they usually succumb to the dropping water temperatures by October. Mero was less than 3 inches when collected and was practically indistinguishable from the baby snowy groupers that are a much more common GSO species. It wasn't until years later that this fish could be recognized as a warsaw and not a snowy.

At a certain size, one way to ID the warsaw grouper is by its extra long second dorsal spine. Here Mero shows off his.

More than any other in the tank this fish loves to be scratched. The divers can make his day by dropping sand onto his skin and into his gills. Mero will open his gill covers wide to encourage this activity.

But what is really happening here? Mero is responding to the touch of the sand the same way he would to the touch of a cleaner fish. Cleaner fish are tiny fish that hang out in particular sections of living coral reefs referred to as cleaning stations. Larger fish like Mero are attracted to these stations. The cleaner fish eat the parasites off of the skin and gills of the larger fish. The cleaner fish get a free meal and the big fish get healthy glowing skin and fresh feeling gills. We don't have tiny cleaners in the GOT but next time you visit the Aquarium you are likely to see this activity with neon gobies involved in cleaning duties on the goliaths in our Blue Hole exhibit. Say hello to Mero while you're here!

-Dan L


1 comment:

  1. Neon Gobies are awesome to watch. Can you see them well from the viewing areas, considering their diminutive size? Any problems with the short lifespan in the big tanks? Must be tough to keep track of them all--do you plan to add more over time to keep up with natural die-off? Just curious.


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