How To Feed Macro Alage to Marine Fishes

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leebca

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BACKGROUND

I guess I’ve taken it for granted that people know how to feed macro algae to their Tangs, Rabbitfishes, Angels, etc. The hobbyist is probably familiar with seeing the local fish store (LFS) feeding their fishes. But that is a one-shot visual observation.

Unfortunately, most LFSs aren’t into keeping their herbivore marine fishes for a lengthy period of time so they may not really get into feeding them long term on macro algae. So I thought this short post on feeding herbivore fishes marine algae is needed.

One other thing. . .When herbivore fishes are very young, they eat a lot of pods and often benthic creatures. The little fishes can’t swim with the large adult and sub-adult schools of fishes that travel the oceans looking for algae. So a true, absolute herbivore marine ornamental fish is really not very common. As the fish gets larger and matures, it turns more and more to algae. These fishes can travel up to 25 miles per day in search of algae AND they just keep eating it. So the goal of feeding in captive life is to mimic that ‘habit’ as closely as possible.




IT’S SIMPLE

The kinds, amount, and frequency is not that difficult to figure and is straight forward.

What to Feed
There is no reason to feed land lettuce, spinach, peas, etc. It was a poor substitute decades ago when sea algae wasn't available. Now that sea algae is readily available, macro sea algae is the only right choice.

I’m not one to advocate feeding any macro sea algae (e.g., nori) that has been roasted or cooked. Watch out for the products that are for human consumption. Some contain additives, flavorings, and even preservatives. DON’T feed your marine fishes these products.

Look for real macro algae, dried by evaporation, without additives of any kind. If unsure, if the package isn’t clear about this, don’t use it. Also, avoid the conundrum of the package saying it is 'roasted' or implies that it was heated, and having someone tell you, 'That isn't true.' In conflict, pass it up.

The main diet of most our marine ornamental herbivore fishes is green algae. The key word here is main. Don’t feed green exclusively. I like 10 feedings of green, 1 of purple, 2 of red, and 1 of brown as a normal rotation. I mean by this that all 10 green feedings aren’t done back to back. Stagger the feedings.

Note that most Angels should be eating red macro algae. If your community tank includes Angels, up the frequency of feeding red macro algae (20%).

Lastly, vary the source. Don’t just keep buying one brand of macro algae. Switch sources/vendors/suppliers. Don’t buy more than your fish will need for 3 months and store it in the refrigerator as soon as you open the package.


The Amount
You put in the macro algae into the display tank (or quarantine tank) on a clip, banded to a rock, anchored by a rock, etc. in such a quantity that after about one hour, only a little bit of it is left. Have you been feeding less? Then you haven’t been feeding enough. That is the goal, plain and simple. After one hour there should be a tiny bit of the macro algae left uneaten.

You experiment at the start to see how much that macro algae is, in order to achieve the above. Then, you can back off of it slightly (cut back a very little) and that is the proper amount. BUT. . .

You should know that if you haven’t been feeding your fishes enough up to this point, that they will likely gorge and overeat for a few days. Until they come to realize that you will not take it away from them, they will act excited and ravenous. But after a while, they may eat less. Just be prepared to recognize a change in their ‘attitude’ toward the feeding and adjust the quantity again so that only a little bit of it is left after one hour.

As you feed the different colors/types of algae, you may find some of your fishes will not eat it or eat less of a certain color. Be prepared to put in less of those colors and more of the colors they eat. That is, be aware that the fish will eat different quantities of different kinds of algae. Adjust quantities to the above goal.


How Often
No less than twice a day. You want to feed the above quantity no less than twice a day.

Once into the pattern, you should see your fish eating less, their attitude ‘calming down’ and even how they treat each other should show an improvement (more tolerant of their tank mates).


Cha. . .Cha. . .Cha. . .Cha. . .Changes
Everything changes. The quantity of food the fish needs also changes. Monitor the quantity you provide routinely. As noted above, at the start the fish may eat more. After a while they will settle into a ‘quantity’ routine. But don’t let that put YOU into a rut. The fish are growing and will need more over time. Always watch and be sure you are still feeding enough/the proper amount.



Keep you herbivore fishes healthy! Remember to still feed some fleshy foods, especially pods, and check the sticky in this Forum for suggestions on the proper foods, vitamin and fat supplements, etc., under Fish Nutrition.
 
Last edited:
Lee, great article!! Can you give some advice or suggestions on the feedings of natural macros from our refugiums? I've got a Spotted Rabbitfish that absolutely LOVE Grape Caleurpa. I feed dried Nori, both green and red, on a regular basis and Gracillaria. My Coral Beauty, Lawnmower Blenny and Spotted Rabbitfish play "tug-o-war" with it. On occasion, I'll take a clump of Grape Caleurpa out of my fuge and put it in the clip. The Rabbitfish goes nuts for it, shreading it apart, and leaving pieces floating all over the tank. The Coral Beauty then swims around eating these floating pieces. I've never worried about the macro taking hold and growing in the display because the rabbitfish eats every last bit.

However, I've heard that it can be toxic and shouldn't be fed on a regular basis. Any thoughts? I also have Feather Caleurpa, Mexicana, growing in another fuge and feed it once in awhile. Not as often because I don't have an unlimited supply of it, as I do the grape. Lastly, what about Chaeto? I've never tried feeding it, but hear some people say their tangs and rabbitfish love it!! Are these growing macros healthy or are there problems we need to watch for?
 
You'll find information about living macro algae foods for marine fishes in this post: Macro Algae for Tangs.

Chaeto can be problematic. Some fishes do eat it, but most have been reported to leave it alone.

I know of no macro algae that would be common to the home aquarium that an ornamental marine herbivore fish should not eat. The common ones are listed in the post linked above.

If you come across literature or a reference where specific algae are said to be poisonous or in anyway not good for our marine fishes, do please let me know. :)

 
Another great write up on feeding fish. Thank you Lee.

As you may remember I followed this advice when you gave me it a while back. My Tangs became a lot more peaceful once I started feeding them enough! They now casually eat their algae rather than gulping it down. Their attitude towards each other is also much calmer. When I compare the way I feed them now to what they were getting, I feel bad as they must have been constantly hungry before.

Thanks again Lee.
 
Thanks Kris. Feeding macro algae like this comes close to simulating what the fishes are used to in the wild. They nibble at algae all day long only stopping for nesting and procreation activities. :D

At the LFS you might see the help putting in a sheet of algae to have it attacked by the fishes, disappearing in a few minutes. Think of this as I mention that these fishes are known in the wild to eat up to 20% of their body weight, each day. Now imagine how much that sheet 'weighs.' Compare that to the estimated weight of the fish times 0.20. See how far apart the two numbers are?

Herbivores are the 'cows' of the ocean, consuming vast quantities of algae. And thank goodness, too! Otherwise parts of the ocean would be a swamp of algae.
 

Herbivores are the 'cows' of the ocean, consuming vast quantities of algae. And thank goodness, too! Otherwise parts of the ocean would be a swamp of algae.

Very true, every time I dive I see lots of blue and yellow tangs along with plenty of surgeonfish. The only time they aren't eating is when they are trying to get away from you so they can enjoy their meal in piece. Even then they usually don't move.

From diving I think most fish eat more than many in the hobby feed them. I know so many people that feed 2 or 3 times a week tops, who believe that is how fish get by in the wild. Maybe for larger fish that may be true, but damsels, wrasses, and the like seem to eat almost constantly.
 

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