Feeding Fish - Basic Health Factors and Care

New England Aquaculture
May 21
3 min read

This article discusses Herbivores, Carnivores & Omnivores (full deep dive here)

Feeding at New England Aquaculture is straightforward, focusing on nourishing fish to promote health, color, and size often not seen in the wild due to predation and health challenges. It's important to understand the types of feeders in an aquarium. While many fish are omnivorous and will eat almost anything, extra care is needed for obligate feeders—fish that are strictly herbivores or carnivores. Some omnivorous fish also show strong preferences in one direction.

Herbivores

Herbivores have evolved to consume plant-based material. Their digestive systems are designed to break down plant life, and anything outside that diet is poorly digested, if at all.

For example, humans can digest a wide range of foods, but roughage like apple peels and corn husks often passes through undigested.
Similarly, when herbivores are fed food they can't digest:
- It may pass through them, but still costs energy to process.
- That energy drain means they require more digestible food to survive.

In the Aquarium

Algae is the primary food source for herbivorous fish.

Species like Rabbitfish and Bristletooth Tangs are obligate herbivores.
While they might consume tiny crustaceans accidentally, their clear goal is algae consumption.
These fish help clean the tank, but:
- They may consume algae faster than it regrows, limiting their own food supply.
- They can be picky—some algae types may be ignored entirely based on texture or taste.

Feeding Recommendations

To avoid malnutrition and support health, hobbyists keeping herbivores should supplement with seaweed and macroalgae daily.

This ensures a balanced nutrient intake beyond what’s available in the tank.
Recommended options:
- Seaweed: Sheets of Nori (like those used in sushi).
- Macroalgae: Hobbyist favorites like Chaeto and Gracilaria.
Feeding method:
- Use a chip-clip attached to a rock or aquarium-safe weight to hold the food in place.
Temporary alternative:
- If you’re out of algae, soak leafy greens (e.g., lettuce) in fish vitamin solutions.
- Use only as a stopgap until proper food is available.

Carnivores

Some fish reject algae and seaweed entirely. Eels, Lionfish, Sharks, and certain Pufferfish are examples of obligate carnivores.

Many possess sharp teeth or beaks for tearing flesh.
“Meat” may include coral and invertebrates—not just fish.
Like herbivores, carnivores also require diet-specific care.

Behavior & Risk

Improper feeding can lead to aggressive or destructive behavior:

A hungry eel may attack tankmates.
Sharks may become frantic or start breaching the surface.
A dogface puffer might begin rearranging rocks in search of food.

These behaviors can result in losses, both to the tank environment and other fish.

Feeding Recommendations

Carnivores may require:
- Live feeder fish for hunting stimulation.
- Meaty seafood as part of their regular diet.
Feeder fish should be:
- Purchased from trusted sources.
- Quarantined in a separate tank to avoid introducing disease.
For varied diets:
- Skip expensive frozen blends by visiting the seafood counter.
- Items like clam strips, scallops, shrimp, and mussels work well.

Prep tip:

Chop and process seafood with added vitamins/minerals.
Freeze in small ice cube trays.
Thaw and drain before feeding.

While frozen foods are abundant, true carnivores don’t require the extra additives found in prepackaged blends made for omnivores.

Omnivores

Many fish marketed as herbivores or carnivores are actually omnivores.

Most saltwater species eat a mix of:
- Algae, crustaceans, invertebrates, and even other fish.
This dietary flexibility makes feeding easier for hobbyists.

Feeding Tips

Omnivores are opportunistic—they’ll sample anything drifting by.
They can easily switch to:
- Pellet or flake foods, which are more convenient than frozen options.
Caution:
- Dry foods often contain binders like wheat germ and pea flour.
- These ingredients can:
  - Rot in water if uneaten.
  - Be indigestible, contributing to excess waste.

Feeding Strategy

Feed small portions multiple times per day.
Only offer as much food as can be eaten in a few minutes.
Rotate food types to ensure all tank mates get fed and waste is minimized.

Even with efficient feeding, strict water change routines are required to control nutrient buildup and maintain tank health.

Get Expert Guidance with New England Aquaculture

New England Aquaculture offers Service and Consultation Plans to guide you in tank care, system design, and best practices. Contact us today to ensure the long-term success of your reef tank!