All marine aquarium fishes are omnivorous. Why do I say this? I mean aren’t there carnivores and aren’t there herbivores? Well sure, but from a husbandry standpoint, it is really best in my experience to think of all your fishes as omnivors and to feed a varied diet for optimal health and well-being.
A big part of good husbandry has to do with feeding, about which I have written here before. One of the biggest mistakes aquarists make in terms of husbandry (again, in my opinion) is not feeding enough, but perhaps the second biggest mistake is not feeding a varied diet.
A varied diet for my own saltwater aquarium fishes includes a combination of fresh and commercially-prepared food of marine origin.
Flake and Pellet Foods
Flakes and pellets are inexpensive, nutritionally appropriate foods IF they are:
Manufactured by a reputable company (you know the big names)
Have not been re-packaged
Are not more than a couple weeks (maybe a month or two at most) old
Flake and pellet foods are accepted by many fishes, and they are probably the least dangerous in terms of adding to the overall nutrient load of your aquarium. You can purchase them in formulations appropriate for different fishes, although I like to mix a pinch of several different formulations on any given day.
In short, flake and pellet food is great. It’s pretty inexpensive, nutritionally appropriate and easy to feed.
Frozen foods should be part of any aquarist’s basic feeding routine in my opinion. If you’re going to buy from a retailer (instead of making your own—we’ll discuss making your own in a later post), go with the well-respected brands kept in the freezer case. A wide array of frozen foods are available from the little gel packs to the frozen cubes to sheets of squid or other meaty marine flesh.
These frozen foods are relatively inexpensive and pretty easy to feed. I like to first rinse frozen food and then thaw it in system water. I then use a turkey baster to target feed thawed, frozen food to my different animals (including invertebrates!).
The downside to frozen foods is that they can, when overused, cause nutrient levels to become elevated as uneaten food decomposes in the tank. Don’t overfeed frozen food!
Fresh Raw Marine Flesh
Your fishes will often appreciate a shrimp, mussel, oyster, or some other piece of fresh raw table seafood. In particular, I like to offer clams, oysters and mussels in the shell to my fishes. I simply open the shell or crack it and then drop it in the tank allowing the fish to sort out how to get at the meat. This is an activity that appears to “entertain” most of my fishes for the better part of an hour, and I usually try to do it about once a week.
Keep in mind that adding a piece of raw table seafood to your tank is, in many ways, like adding a dead animal, and it can have the same effects if uneaten portions are allowed to decompose there. If there are left-overs, it is worth taking the time to remove them from the tank.
In my opinion, avoid feeding “feeder fishes” unless absolutely necessary. Most saltwater aquarium fishes kept by the majority of hobbyists can and should be weaned onto a captive diet. ‘Nuff said.
When it comes to greens, I only feed greens of marine origin (no lettuce for my fishes!). While I think some of the commercially-prepared herbivorous foods are pretty good (and as mentioned above, I mix these in when I feed), nothing is better than growing your own macroalgae in a refugium for the purpose of feeding. A close second, however, is Nori and other marine algae available in the Asian food section of you local market. Avoid anything that has been processed beyond simple drying.
To return to where I began, the vast majority of marine fishes are, truly, omnivores, so mix it up to be sure that all your animals get a varied and nutritious diet. Do your homework, know your fishes natural diet and be sure to use feeding time as an opportunity to observe your fishes’ overall health and well-being.