by Ret Talbot with Photography by Bob Fenner, David Bellwood, John O'Malley, A. Gonzales, & Jose Reyes
May 2009 in Tropical Fish Hobbyist
 Herbivores occupy a critical ecological niche in the marine environment. While mollusks take the lead controlling marine algae in the intertidal zone and in our aquaria, herbivorous fishes fulfill this role on tropical reefs the world over. While aquarists with fish-only systems may rely on herbivorous fishes to control algae, algae-grazing fishes can and should be enlisted in this capacity in all aquaria. Although this may at first appear a straightforward task—simply select and acquire a fish identified as an herbivore that is compatible with your system and other livestock—recent research has shown that it is not quite so easy.
Researchers in both the Caribbean and the Indo-Pacific are learning that an herbivore is not an herbivore is not an herbivore, and much of the conventional wisdom regarding algae-grazers is, in fact, misleading. The marine aquarist familiar with this research is in a position to be a more informed and conscientious aquarist with the husbandry skills necessary to select and care for these remarkable animals.
Why Control Algae?
Controlling marine algae growth is critical on tropical reefs and in reef aquaria. Once established, macroalgae prevents new coral recruits from effectively competing for space and induces what is a called a phase-shift away from a coral-dominated habitat to an algae-dominated habitat. As such, herbivorous fishes which graze on algae fulfill an essential....
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To read the entire article, please purchase the May 2008 issue of Tropical Fish Hobbyist by clicking here. Tropical Fish Hobbyist magazine is the best source of accurate, fascinating, up-to-the-minute information on the aquarium hobby, from small freshwater tanks to wall-sized reef tanks and even beautifully landscaped garden ponds.
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Ret is very pleased with this feature article as it merges his passion for the hobby with his penchant for marine science and strong conservation ethic. "Understanding the ecological niches of fish, both on the reef and in the aquarium," writes the editors of TFH, "can help elucidate why things like algae outbreaks happen and how to fix them when they go wrong. Our author summarizes recent research on herbivores, with some surprising findings that every reef aquarist should know."
I am particularly appreciative of Dr. David Bellwood's assistance with this piece. Bellwood is a researcher associated with the ARC Centre of Excellence for Coral Reef Studies and a professor at Australia’s James Cook University. Bellwood’s research focuses on the function of reef fishes within their ecosystems on the Great Barrier Reef. As part of his research, Bellwood and his team planted macroalgae assays—a common research technique—on a portion of reef and watched and waited. “To our surprise and disappointment,” says Bellwood, “the fish that usually ‘mow’ the reef—parrotfishes and surgeonfishes—were of little help when it came to suppressing well established weedy growth. Most herbivores simply avoided the big weeds.”
While it may have been surprising to Bellwood to see the best-known grazing herbivores associated with coral reefs ignore the macroalgae, what he saw next astonished him. Caught on underwater video footage, Bellwood watched in amazement as his macroalgae was consumed by some very unusual suspects. You'll have to read the article to find out who...
PHOTO: David Bellwood
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