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Fly on the Wall 

May 13, 2010

Venomous Fish Reproduce (and Rewrite Song Lyrics)

Aquarium biologists have succeeded in spawning the lacy scorpionfish, Rhinopias. This is the first documented case of captive reproduction in this genus, which was extensively studied by a former Academy scientist, Bill Eschmeyer. Here is a picture of the proud Rhinopias parents.

These venomous fish are not overly abundant in the wild or common in the aquarium industry. They don’t have the best track record in captivity, often living for less than two years. Academy biologists thought very hard before deciding to put them on display, but were confident they could provide them with high-quality animal care.

Things seem to be working out, fish style. Since going on display last November, the two individuals have been eating well, regularly shedding their skin (a normal behavior for Rhinopias), and challenging guests to spot them among the corals.

I will admit that the ever-active whimsical lobe of my brain has sprung into action to imagine how Tin Pan Alley would have been different if people, too, signaled contentment with their lives by regularly shedding their skin. Song lyrics would be very different. “I’ve Got You Under My Skin” would need a new second verse. There surely would be a new take on that great song sung by Frank Sinatra and Ella Fitzgerald: “There I go again. About to shed my skin again. All aglow again. Takin’ a chance on love!” And so forth.

But I digress. Back to the fish.

In early March, Academy biologists found an egg raft in the Rhinopias tank. Eggs signal mucho happiness in the piscine set, even more than skin shedding. The eggs were hard to spot because they are almost completely clear. It’s possible that they mimic a comb jelly to discourage predation. Should you wonder, a “comb jelly” is an animal that looks like a jellyfish and behaves like a jellyfish, but is a different animal altogether. Since it’s transparent and about the same shape as the egg raft, it would be easy to mistake one for the other.

Our biologists have asked around among those who would know, and it appears that these are the first Rhinopias eggs that have been laid in captivity, or at least the first that have been observed and reported. The biologists assumed the eggs were infertile, and then were surprised to see them develop, and even more surprised when they hatched. Two batches of eggs have now been laid, and it has been amazing to watch the larvae develop: growing fins, a mouth, and a gut where none existed before.

Feeding really tiny larval fish of this sort is a major challenge, so every day that they survive is another triumph. Pictures of the larvae at day 2, 3, and 8 are shown below.

The scorpionfish parents live in the Water Planet exhibit (Lower Level), next to the Burmese vine snakes. Come and visit!

Filed under: Aquarium,Sustainability — Greg Farrington @ 10:17 am

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