I am glad you looked into this a little further. I have never personally kept a hippo tang or had any major desire to do, so I never really read up on them that thoroughly. However recently I have started to take care of some tanks which have these fish in them which are suffering from malnutrition.
From what I am reading it seems what is true for other surgeonfish is true for this one in that most of the time lack of food is more of an issue then the type. Though it seems a well rounded diet for Hippo tangs should include a larger percentage of meaty items then it would with most other surgeonfish. It would seem as some people would go as far to call the Hippo tang a planktivore. While other sources would say they are grazers that require some meaty foods in their diet. No one can argue though that they need to be fed often.
I would have to agree with Ian to use caution with your sources.
It would probably be a good time for us to have a presentation at a regular meeting on sources for information in this hobby. While I won’t really work to discredit the above sources keep in mind a couple of them come up in google searches not because they are the authority on the animal or know the animal well, but because they probably have a staff dedicated to staying high on the google list and spend money to do so. The other reason these sites are not the greatest source is sites like these are notorious for down playing the difficulty of animals to attempt to make a sale. While many of the reputable sites such as some of the above sources have improved significantly in the last three years I would consider their advice right up their with the majority of LFS employees.(consider it and look for more sources)
Here are a couple of extra sources I would trust:
Wet web media
“Stomach contents analysis of wild Paracanthurus show that this fish is omnivorous, consuming benthic and planktivorous invertebrates and attached algae. Aquarium diets need be diverse, fresh and encompass some nutritious “green” material on a daily basis.
Further, your close watch to ascertain that your palette(s) are eating is called for. As feeders they can be driven away by bullying tankmates, and sulk away to dangerous thinness. In my estimation, a lack of nutrition and outright food are the key reasons for loss of these fish.â€ÂÂÂÂÂÂÂ
Michael Scott (2001)
“Meaty foods to satisfy its zooplankton diet, including finely chopped fresh or frozen shrimp, mysid shrimp, and vitamin-enriched brine shrimp. It will also eat frozen preparations for herbivores. Feed at least 3 times a day.â€ÂÂÂÂÂÂÂ
Delbeek and Sprung (2005)
“Paracanthurus hepatus, the blue, regal, hepatus or hippo tang is also an algae grazer, though in nature it feeds heavily on zooplankton. Nevertheless, it can be an effective grazer for a reef aquarium, and it should be offered dried seaweed to supplement its diet if it has little algae to graze. This tang often does not do well in the aquarium once it reaches adult size. They will often show aggression towards conspecifics, especially if more than one male is kept in the aquarium. This species in unpredictable in its behaviour towards coral and has been reported to feed on Sinularia and other corals (B. Shepherd pers. Comm.). The spines are also venomous.â€ÂÂÂÂÂÂÂ
(They also point to, “An excellent guide to surgeonfish and rabbitfish species identification, diet and ecology is Dr. John Randall’s book Suergeonfish of Hawai’I and the World.â€ÂÂÂÂÂÂÂ)