Reader Gary Walden snorkels most days in Ko Olina Lagoon No. 4 and emailed the following, with a picture: “I cannot find the name of this fish.”

I didn’t know the fish name either, but thought it was probably one of Hawaii’s rascally wrasses. Those reef fish are tricksters to us snorkelers because worldwide there are 460 species in the family, and of those, Hawaii hosts 43.

That might not be so hard to sort out, except that some baby wrasses look so different from their parents that in the past, researchers considered the youngsters separate species and gave them their own scientific names. The true identity of the young wrasses became apparent when they gradually changed into their adult colors.

As if that’s not enough to confuse even seasoned fish watchers, some wrasses change body color dramatically after they’re adults, switching from female to male as the need in a wrasse harem demands.

Since I was feeling a bit under the weather when I received Gary’s email, I carried my fish ID book to the couch, lay back and started paging through wrasse pictures. Nothing, however, popped out resembling the Ko Olina No. 4 fish. Frustrated and sleepy, I tossed the book toward the coffee table where it fell off the edge.

And behold! When I reached down to pick up the guide, there was Gary’s fish staring up at me. The guide had fallen open to the snapper family and lay open on the precise page.

Gary’s fish is called a blacktail, or flametail, snapper, Lutjanus fulvus. The blacktail snapper has no Hawaiian name because it’s a Tahitian fish, not native to Hawaii waters. Tahitians call it to’au.

Hawaii hosts only two native coral reef snappers (we have three deep-water species: opakapaka, ulaula and onaga) and since snappers are delicious, in 1956 state fisheries managers brought blacktails here from Moorea, an island in French Polynesia.

Those snappers were roamers. Only weeks after their release in Kaneohe Bay, anglers caught them in North Shore’s Waimea Bay and others were caught off Honolulu.

To’au never became abundant, however, and in 1958, officials tried again, this time bringing to Hawaii bluestripe snappers, called ta’ape in Tahitian, from the Marquesas.

Although the introduction was well-intended, bringing the 12- to 13-inch-long fish to Hawaii was a mistake. Even though the ta’ape did well in Hawaii waters, and the to’au are hanging in there, they never caught on as food fish. A third introduced species called the paddletail snapper is rare here today.

Even so, Hawaii’s immigrant snappers have their charms, being attractive and — who knew? — psychic too. The next time someone sends me a snapper picture, I’ll just throw my fish book at the wall and let the fish find itself.

Reach Susan Scott at susanscott.net.