All herbivores are not created equal

[BigJay]

I read an article called "All herbivores are not created equal" in the recent TFH magazine. At the heart of the article was a field study on what kind of fish were eating which algae on a reef. Most of the common algae eating fish (rabbits, tangs) would barely touch large algal growths (sargassum in this case). However, these fish would feast on smaller tufts of the same algae with great gusto. It was actually a species of batfish that did significant damage to larger growths. Apparently some algae eating fish are useful at controlling algae on the reef when there isn't much of it, but useless at turning around a reef already taken over by algae (due to overfishing, run off, etc).

Anyways, my question is does this have any relation to what algae fish will eat in the aquarium? I've noticed that pygmy angels are only interested in the film-type algae, they leave the longer hair algae alone for the most part. They won't eat the clip nori, I surmise because it's too big. So I added less nori to the tank, so that less than 1/4" was exposed past the clip. Not surprisingly, they actually ate most of it where as before they wouldn't go near it.

I hope I brought up an interesting topic, sorry if I bored anyone.

 

[ChuckLawson]

Interesting. After seeing someone else do it, I've recently taken to rolling up my nori in a tight tube, and then clipping it. It seems that a lot more of my fish are interested in it (including a Potters and a bicolor blenny), and I don't have nearly as many pieces of nori torn loose and floating around the tank.

Re: ignoring large algal growths; I wonder if it might be a recognition problem? I've had a number of occasions where tangs and rabbitfish would completely ignore a (sometimes large) patch of algae (both hair and macro algae) and then one day they'd mow it into oblivion -- kind of like they hadn't realized it was food up until that point.

 

[gabbagabbawill]

I have noticed this same behavior with feeding nori, and have thought that maybe they were intimidated in some way by the larger pieces.

 

[daytonben]

I've noticed this behavior before too and been completely confounded by it.

 

[reefer31]

thats a good idea about rolling the nori because after about 20 seconds after i place nori in my tank my sailfin and purple tang just rip the crap out of the nori and most goes to waste. Anyways, there are different fish that will eat different algae. Just look at the mouths of different tangs or other herbivorous fish for that matter. Bristle tooth tangs mostly rasp algae/diatoms and detritus while the zebrasoma tangs eat algae in crevices/small tufts of algae but mostly softer stuff I have noticed besides chaeto. The differences go on but I also have noticed that lawnmower blennies will eat hair algae relatively well and also algae film. So I guess all the different fish have a different role/diet when it comes to algae. But, sometimes I think that once the algae has gotten out of control, it takes something else to cut it back, maybe sea turtles/ even larger fish.

 

[reefer31]

or urchins...forgot about those guys