Feeding your fish is fun! Seeing an animal devour and reap the benefits of the diet you have chosen, made, caught or created is both enjoyable and rewarding. With that said, when the animal refuses to eat, panic soon ensues and what should have been a fun experience soon becomes a significant concern.

While most of the common, commercially raised tropical fish kept in aquariums today are easy to feed, there are exceptions to the rule. In this review, we will explore factors and considerations that influence feeding, as well as the various tactics you can employ to get those fussy feeders to start eating properly!

Environmental Husbandry

Keeping tropical fish in the right environment means not only ensuring the right temperature range, water chemistry, water movement and filtration, but also the aquarium setup with regard to decorative structure and tankmate choices. Fish are poikilotherms, which means they cannot generate enough body heat to sustain a constant and consistent body temperature as mammals can. Rather, they are “cold-blooded” – their body temperature varies with the temperature of their environment. When considering a new specimen for your aquarium, always make sure its ideal temperature range is accounted for: if this parameter is incorrect, it would be normal for the fish to not feed properly due to a resulting drop in its metabolic rate. A daily regular check of your thermometer can go a long way to avoid issues with fish feeding response.

While many species of tropical aquarium fish tolerate fairly wide pH ranges, it is recommended to maintain them within their preferred range. Incorrect water chemistry can contribute to lethargy and an overall less responsive fish, potentially impacting natural activities such as feeding.

Keeping fish with adequate filtration at their preferred water current level does contribute to natural behavior and supports a proper feeding response. This is especially true for shy species, such as some of the dwarf anabantids, small species of pencilfish and many killifish. Some basic research on the conditions appreciated by the species goes a long way to supporting the expected feeding response. The same can be said for lighting levels: extremely bright illumination can upset shy species that prefer feeding in dimmer conditions.

Stocking numbers of conspecifics is also a key point. Many fish species feel far more comfortable and are far more likely to feed properly when in the presence of a group of their own kind. Newly imported wild discus, for example, are more willing and will more quickly accept and adapt to prepared foods in larger groups of 10 to 15 fish, rather than if kept singly or in much smaller groups of 2 or 3 fish.

Wild Versus Commercially Farmed

Commercially farmed fish are usually well adapted to a variety of dry foods and are not a challenge to feed. Wild fish, on the other hand, can arrive post-capture with various parasites that need to be treated, and are used to feeding on a diet of live foods that is often not available to them once in captivity. This combination ultimately inhibits wild fish from feeding once they arrive in your aquarium. As mentioned above, creating the right habitat is key in these circumstances. Once the fish have settled in, it is usually possible to coax them onto frozen food, such as freshly defrosted bloodworms, which are similar to live foods in both taste, texture, and appearance. As the fish devour more of the frozen food, it is recommended to mix in small quantities of a quality granular or flake food, and to gradually increase their intake of prepared dry commercial foods over time.

Marine vs. Freshwater

There are a greater variety of marine species that are imported for aquarium keeping that are specialized feeders than freshwater species of tropical fish. Thankfully, the industry is aware of this and the situation is being addressed.

Many marine butterflyfish (family Chaetodontidae) are highly specialized feeders in their natural habitats. In the home aquarium, some can be accommodated by certain fresh foods such as clams, or by adhering food mixes to “feeding rocks” to recreate their natural feeding behaviors. Other species, such as those that feed exclusively on live coral polyps, are unlikely to ever adapt well to commercially prepared diets and as such should not be kept in aquariums. One such example is the Orange Spotted File Fish (Oxymonacanthus longirostris): while some claim it can be weaned onto certain fresh and frozen foods, they are known coral polyp feeders and as such are much better off­ in the ocean where they have an abundant supply.

Additionally, there are other saltwater species that, while they will accept food in captivity, seemingly do not obtain all of the nutrients they require. The Moorish Idol (Zanclus cornutus) is one such example, and as a result is rarely seen in aquariums these days.

Choosing the Right Species

Doing some research and understanding the environment, water conditions and preferred feeding habits as well as specific foods your targeted fish require is important for long-term successful fishkeeping. When you first acquire new fish, it is recommended to quarantine them, ensure they have appropriate structure in the aquarium to help them feel secure, and avoid startling them.

When planning for which fish you will keep in a community tank, compatibility is key: fish will not feed properly when they are being bullied or consistently chased. Consider the level at which the fish will spend most of their time: mixing fish that inhabit diff­erent levels of the aquarium is recommended, as this will avoid fish being crowded at any particular level, while also allowing each type of fish a greater chance of feeding at the level it prefers.

The keeping of interesting predators such as pike cichlids, gar species, and characins such as Boulengellera are examples of fish that prefer live foods but that can be coaxed into consuming fresh or frozen substitutes. Eventually, by mixing in dry formulas with fresh or frozen foods, they can learn to accept them. There are important advantages to weaning any of these types of fish onto prepared diets: first, the availability and consistency of the quality of the food, and second, the avoidance of introducing parasites via the addition of feeder fish.

Dry Formulas

The raw ingredients, type and size of food off­ered also plays a significant part on getting those tougher to feed species to eat. Small sinking granular foods for small, shy species with small mouths such as licorice or chocolate gouramis are important. Fluval Bug Bites Tropical Micro Granules are a good choice for species such as these, given the ideal size of these granules, their palatability, and the high inclusion of black soldier fly larvae and other quality ingredients.

There are many factors to consider when keeping tropical fish species that can be naturally fussy feeders, and all of them are important. Patience and making the right decisions are key: some of the most enjoyable results come from that extra eff­ort!