To better understand fish and invertebrate feeding habits, let's first take a look at each feeding category.
- Carnivores eat a main diet of other marine fishes, crustaceans and invertebrates. These animals are categorized as predators and/or scavengers. Predators spend their life hunting or lying in wait for an unwary meal. When a meal is consumed or they have had their fill, many species will not eat again for a day or two, sometimes longer. Scavengers are opportunistic feeders, generally eating the left overs from other predators, and most will eat detritus as well. For fish, Cardinals, Dottybacks, Eels, Frogs/Anglers, Grammas, Groupers, Hamlets, Hawks, Lions/Scorpions, Pipefishes, Porcupines, Puffers, Seabasses, Sharks, Snappers, Soldierfishes, Squirrels and Triggers are predators, and most are also scavengers. Even though some Hermit Crab, True Crab, Shrimp and Starfish species are herbivores, most are carnivorous or omnivorous, and all types should be considered scavengers. Some will eat or pick at sessile (attached at the base; stationary) invertebrates and corals, coraline algae, and may even attack other fish or tank mates and inhabitants. Many Anemones are considered carnivorous, but some fall into the filter feeders category as well.
- Herbivores eat a main diet of marine plants and algaes. These animals spend their entire day cruising and grazing, picking here and there when a food source is found. Fish that fall into this category are Tangs, Surgeons and some Blenny species. Some species of Sea Urchins, Hermit Crabs, True Crabs and Starfishes are herbivores, but most are considered omnivorous, as well as scavengers as mentioned above.
- Omnivores eat a combination diet of corals, small crustaceans, inverts and some marine plant life. These are not predatory fish, but some species will sometimes pick at fleshy foods as well. Fish that fall into this category are Damsels, Clownfishes, Cow/Boxfishes, Anthias', Blennies, Gobies, Dottybacks, Filefishes, Goatfishes, Seahorses, Spade/Batfishes, Sweetlips, Wrasses/Hogfishes and Moorish Idols. Angels and Butterflyfishes are considered to be omnivores, but some species mainly or solely feed on corals and/or particular sponges. Parrotfish are considered to be strictly coral eaters.
- Suspension or filter feeders are either sessile animals that derive their nutrition from filtering out nutrients and microscopic foods suspended in the ocean water, or sand sifting animals that filter foods from their substrate environment. Animals like corals, tube worms, sponges, tunicates and the like are suspension feeders, while sea cucumbers, some species of starfishes, marine worms and other similar inverts fall into the filter feeder category. Mandarinfish/Dragonets, some Blenny, Goby and other similiar fish species are predatory sand sifters. They search for tiny crustaceous copepods and amphipods to feed on, and require a good healthy population of them in the aquarium substrate to survive.
