In recent years, fish farming has taken off big-time, becoming a virtual “blue revolution.” The theory is rather than exploit the wild stock of fish species, it is better—and more convenient—to raise food fishes in controlled conditions, be that on land and pens at sea.

Fish farming has impacted the market to such a degree that now aquacultured fish has become the forth-largest source of farmed meat. But, as expected, fish farming is not as easy as it might seem. Besides all the environmental and social concerns that many people have expressed, successful fish farming requires constant monitoring and vigilance. So many things can go wrong: the water can become oxygen depleted or contaminated; the enclosures can become overcrowded; or unwanted predators may help themselves to easy meals.

However, despite all of these problems, fish farming has been around for a long time. From ancient times, various peoples have reared certain fishes in controlled environments. The Romans, for example, had special ponds where they reared moray eels, which were considered to be culinary favorites, while carps and goldfishes have been kept for centuries as ornamentals in China.

But way before people ever came up with the idea of farming fishes, there were fishes that were farming. And they are still at it today.

Among the most famous of these farming fishes is the one appropriately called “farmerfish” (Stegastes lividus). This damselfish is in many ways a wide-ranging species, being found throughout the Indo-Pacific, from the Red Sea to the Line Islands. Yet its range of habitats is very, very narrow, being almost exclusively among the branches of staghorn coral (Acropora spp.). There, an adult farmerfish will stake its claim and set about tending filamentous red algae which grow on the lower portion of the coral. The farmerfish feeds on these algae, carefully tending the plants, even letting patches that were recently harvested lay fallow so as to assure a continuous supply. Numerous farmerfishes often set up virtual colonies, but this is not a case of “share cropping” by any means. Each farmerfish zealously and jealously guards its personal garden plot against all intruders, be these others of its kind, bigger fishes or even inquisitive divers. The farmerfish is almost as famous for its tendency to attack divers as it is for its agricultural skills.

In the waters off of California, another pugnacious damselfish has gained its own reputation for attacking divers. This is none other than the bright orange garibaldi (Hypsypops rubicundus). And often the motive for such aggression is the same as with the drab colored Farmerfish—someone trespassing in the fish’s private garden!

All California divers know that garibaldis are not all that limited in their habitat. They are equally at home around kelp forests, rocky outcroppings and pier pilings. However, when it comes time for raising the next generation, well, that’s different.

An extreme domestic urge comes over, no, not the female, but the male garibaldi. Mr. Garibaldi will choose a portion of a rock and then meticulously remove everything growing there. Then, he sets about cultivating filamentous red algae. And not just any old red algae will do, but only a few species, Murrayellopsis dawsonii and Spermothamnion snyderae being favorites. No unwanted weeds allowed in this farm, that’s for sure!

When his little garden-like love nest is all set, then the male garibaldi will try to coax a female in. If he succeeds, she will lay her eggs, between 15 and 80 thousand, depending upon her size—and then the male will promptly shoo her away. He may even woo several females into his abode and end up with close to 200 thousand bright yellow eggs to manage.

During the next two or three weeks, while waiting for these eggs to mature, the male garibaldi faithfully guards his offspring, gently fanning them with his fins. He will fight off any intruder, be they fish or human. About the only thing that will scare him away would be a hungry sea lion. Finally, after the eggs have turned a dark brown, they hatch. Evidently, though, parental care only goes so far with garibaldis and the baby fishies are left on their own to face their unpredictable future alone.

What the future holds for modern fish farming is probably even harder to predict. Many aquaculturists have given up their ventures after realizing that the business is just too labor intensive, that they are never able to let down their guard, day or night. Why, it could be said that to have a successful fish farm, one must have the attitude of those tried-and-true experts in the field, those farming damselfishes themselves!