Cultivating Ogo and Sea Lettuce for Your Tangs

These days, it seems that most marine aquarists are reef aquarists. And reef aquaria almost always house one or more tangs. This should seem reasonable enough, as representatives of this sizeable fish family (Acanthuridae) are found in abundance in pretty much every shallow water coral reef ecosystem on Earth. But their strong presence in the wild is hardly the only reason that they are so often selected for display by saltwater aquarists. Many of them are beautifully (some you could say stunningly) colored and patterned. They are relatively hardy and readily adaptable to normal captive conditions. These are also very bold, active fishes with what some describe as “personality.” Tangs are especially rewarding for keepers who love to feed their fish, as they are notoriously enthusiastic eaters.

One notable characteristic of the family in general, and members of the genus Zebrasoma in particular, is their heavy reliance on algae in their diets. This is particularly remarkable in that algae grow in very meager quantities on most coral reefs. A hyperactive fish such as the yellow tang (Zebrasoma flavescens) consequently must graze nearly all day to meet their basal dietary needs.

Under the usual captive conditions in home aquaria, things might be a little different for a tang with regard to diet. Most significantly, much of what they consume is from packaged dry or frozen fare (not live) and thus likely has lost some palatability and nutritional quality during processing. Not quite perfectly natural in terms of taste and mouthfeel! And, prepared diets almost always have a significantly higher protein/carbohydrate ratio (even those “herbivore” formulas) than the natural tang foodstuff. It fortunately is possible to acquire the real thing–fresh, live seaweed! The best way to accomplish this is to grow it yourself in a great big planted refugium.

Getting your grow on

Yet one more thing that has contributed to the enduring popularity of tangs amongst aquarists are the animals’ habits of consuming nuisance turf and hair algae. Many cite algae control as the biggest reason they keep these animals. But, very quickly, even a single specimen will pretty much eradicate all algae it can reach and begin to grow hungry. The solution? Cultivate a large, lush seaweed bed in an area that is designed specially for plant growth (per substrate, lighting, etc.): A planted refugium!

Let’s just start by pointing out that there are numerous reasons to install a refugium on virtually any marine aquarium system. One common use is to promote large populations of resident microcrustaceans such as copepods (i.e. a place where they can feed, mingle and breed without constant harassment by predators). Macroalgae create a perfect biogenic habitat for pods of all kinds. As they grow, macroalgae also sequester or “absorb” nutrients from the water, thereby competing aggressively with nuisance algae throughout the entire system.

But there is one use of macroalgae that is–despite being so oft overlooked–of extreme value to those who have and love a tang. As the plant material starts to overgrow the environs of the refugium growth chamber, portions of the crop are harvested. This freshly harvested material is customarily thrown out with the trash. What would your tang think, watching aghast from behind a glass panel as you toss out piles of that delicious seaweed… without offering a mere pinch..?

If an edible macroalga is selected for refugium use, then your tangs just scored a regular source of their favorite nutritious snack (so long as you give it to them!). The overall nutritional quality of their diet will be improved yet further if more than a single species/type of seaweed is served.

The perfect palatable pair

Let us just begin by saying that tangs have different preferences for different kinds of macro. Though wildly popular in the hobby on account of its excellent capacity for nutrient removal, Chaetomorpha is definitely not a favorite of tangs or herbivores in general. Therefore, while it is perhaps the best choice for algae reactor applications (where it resists compaction due to its tough, wiry form), this macro is not so great as a live food plant. The reason? It’s like eating a scouring pad. Chaeto is simply too tough for the fish to easily chew.

Guess what? There are not just one but two incredibly hardy macroalgae species that sequester nutrients at just as high a rate as chaeto and are extremely palatable to fishes. When you vary the animal’s diet by using more than a single source species, you provide a better diet compared to either species alone. And even though we’re mainly talking about mostly utilitarian applications here, it’s worth pointing out also that the two differ from each other in a complementary way aesthetically and arguably look much nicer together. This amazing duo is? The red algae red ogo (Gracilaria parvispora) and green algae sea lettuce (Ulva lactuca).

AlgaeBarn’s own Clean Sea Lettuce™ is bold and leafy and very, very green. Its broad fronds provide a massive amount of surface area for pods to forage on and hide within. This nitrate-phosphate sponge appreciates regular replenishment of trace elements (such as iron). AlgaeBarn’s fast-growing Red Ogo improves the seaweed bed structurally in that its frilly, lacey, bushy fronds act as spacers that allow for more thorough water circulation (i.e. improved aeration, waste dispersal, etc.). This trait is especially beneficial when the species is co-cultured with Ulva, as fronds of the latter have a tendency to cling together like sheets of wet paper when grown alone. Best of all, both are offered as selections in the CleanMacro™ Series of pest-free seaweeds. Your tangs couldn’t have gotten luckier!

3 thoughts on “Cultivating Ogo and Sea Lettuce for Your Tangs”

  1. Stefanie Grober

    We use chaeto in our sump , works great! Will have to buy some sea lettuce to grow, we’ve always fed dried seaweed

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