Fish of the Month: Stripey Microcanthus strigatus

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FISH OF THE MONTH - SEPTEMBER 2003

STRIPEY
Microcanthus strigatus (Cuvier, 1831)

Lydgate State Park, Kaua`i. 3 ft.

STRIPEY
Microcanthus strigatus (Cuvier, 1831)
Here is a distinctive Hawaiian fish that almost no one sees. It's not exactly rare--you just have to know where to look. I first read about this species in Tinker's Fishes of Hawai`i. Tinker reports that the young "are found in the shallow waters of the shore line in April and May and move into the deeper water on the outer side of the reef as they mature." Dr. Randall's Guide to Hawaiian Reef Fishes says that "the young can be caught in tide pools from December to April." Gosline and Brock in their Handbook of Hawaiian Fishes state that the species is "not uncommon in certain shallow water areas." Now I had spent a lot of time peering into tide pools and had never seen a Stripey. Nor had I ever seen one in deeper water beyond the reef. And in all my hours spent snorkeling in shallow water I had not seen any stripeys at all. Not one, ever. I asked other divers, but no one was seeing these 6-inch fish with the bold diagonal stripes. I mean if you saw one of these guys you could hardly miss it, could you? So where are the stripeys? All the fish books said they are here. I was desperate to find one.

Finally my wish was granted. While on Kauai to photograph Whiskered Boarfish I asked Linda Bail of Bubbles Below Scuba Charters where I could find stripeys. “Lydgate State Park” she told me. I went there and sure enough, along the rocky breakwater on the seaward side of the shallow snorkeling lagoon I was thrilled to find dozens of stripeys. The kids were feeding them bits of bread. (There was even a small morwong back in the rocks too, another first for me at the time.)

Lydgate State Park, Kaua`i. 3 ft.

So.... where else in Hawai`i can one find stripeys? On O`ahu I have since seen them in Honolulu Harbor, at Hale`iwa Beach Park, off the Episcopal camp near Mokule`ia, and near the canal outflow near the Kahala Mandarin Hotel in Kahala. Stripeys are also reported from areas of Kane`ohe Bay, although I've never encountered one there. All these spots, with the possible exception of Mokuleia, have something in common with Kauai’s Lydgate State Park, they are sheltered locales with at least some rocky bottom where fresh water mixes with sea water. (Lydgate is adjacent to the outflow of the Wailua River. Mokuleia is sheltered and rocky, but I don't remember any fresh water mixing with sea water). Dr. Randall’s book says that stripeys will enter brackish water, and I think this is the key. If you want to see stripeys, snorkel around canal entrances, harbors, and the like. If you find any stripeys in a purely marine environment, I'd like to hear about it.

Mokule`ia, O`ahu. 8 ft.

Three species or one?
The Stripey is found in Hawaii, Japan, and the China Sea north of the equator and around Australia south of the equator, but nowhere between. The two populations are a long way apart. Ichthyologists have traditionally considered all stripeys to belong to one species, but Australian Rudie Kuiter has tentatively separated them into three: the Northern Stripey (Japan and Hawai`i), the Eastern Stripey (eastern Australia), and the Western Stripey. Kuiter does this on the basis of subtle but consistent color differences. Not all ichthyologists would agree with Kuiter. Dr. Randall, for example, generally wants to see some physical differences other than color before declaring a fish to be a separate species. The classical test, but one seldom practical to perform, would be to confirm that the two populations can interbreed. If they cannot interbreed they would definitely be separate species.

Now here is something interesting: it turns out that Dr. Randall got his information about the young appearing in tide pools from an Australian publication, describing (no doubt) stripeys from Australia. In Hawai`i, as far as I can tell, the young do not occur in tide pools. This observation might support Kuiter by indicating that the northern (i.e Hawaiian) population has different reproductive patterns than the southern populations. If so, the two are likely distinct species. Well, that’s my two cents on this controversy, anyway.