Breeding Aquarium Fish: Your Questions, Myths About Feeding, and the Dark Side of Large-Scale Farming

Breeding aquarium fish is a lifelong passion for many, bringing constant discoveries of new insights. In the latest episode of the series Conversations Above the Surface, renowned aquarist Josef Pejša shares his rich experiences. Josef Pejša is not only a successful professional aquarist and well-known breeder of discus fish, but in the past, he also bred over 50 species of African cichlids simultaneously and gained insight into the issues of industrial fish farming.  

What does breeding discus fish involve, how to prepare the right feed mix, and what happens behind the walls of fish factories?  

Cichlids from Lake Malawi

African cichlids from Lake Malawi are an ideal choice for beginners due to their attractive coloration and high resilience. Compared to fish from South America, they can tolerate much higher levels of nitrogenous substances in the water. They are less demanding on water quality than cichlids from Lake Tanganyika, which quickly stop thriving under deteriorating conditions.

However, when breeding them, it is essential to remember their behavior:

Fish from Malawi are relatively territorial and require plenty of hiding places. Once you have an established group, introducing new individuals is very difficult, as the original inhabitants can eliminate them.  

The water in the aquarium for these African fish can be maintained at the correct pH levels using regular baking soda and limestone. Interestingly, visibility in Lake Malawi is proven to be worse than in Lake Tanganyika. Josef Pejša believes this is due to higher eutrophication of the water—meaning a higher content of nitrogen and phosphorus. The abundant presence of phytoplankton and algae is likely also the reason why local fish grow to larger sizes. Due to their long digestive tract, Malawi cichlids require a significant proportion of plant-based food; Mr. Pejša has previously supplemented their diet with salad, oatmeal, or boiled pasta letters.  

Controversial Topic: Does Beef Heart Belong in Fish Mixes?

Among aquarists, there is still a myth that feeding fish specifically beef or turkey heart is completely unnatural and harmful. However, Josef Pejša refutes this opinion and refers to history. The pioneer of this trend was world-renowned discus breeder Jack Wattley, who conducted very successful experiments with heart feeding. Many European farms, such as the famous Diskuszucht Stendker (which ceased operations a few years ago), exclusively fed their stocks with mixes containing beef heart and consumed tons of it annually.

Fish are adapted in nature to survive by eating things that are not entirely common in their environment and can digest them, “

Those opposed to meat feeding are advised to look at the composition of common commercial pellets from large manufacturers—often they contain dried milk products, flour, or eggs, which are ingredients that fish encounter in nature just as frequently as cows.  

Feeding with meat mixes, however, has its clear rules:

• It must not consist of pure muscle meat: In nature, fish consume entire animals, including skin, bones, and digestive tracts full of enzymes. Pure muscle meat is not sufficient, and the mix must be balanced.  
• The necessity of plant components: Discus fish are omnivores and need indigestible fiber in their diet. Josef Pejša successfully adds boiled young nettles from his garden or frozen spinach to his meat mixes. This way, the food is better digested by the fish, and their waste stays together, preventing water from becoming cloudy.  
• Vitamins and minerals: Homemade meat mixes can easily be enriched with beta-carotene for better coloration of the fish or vitamin D to boost immunity and resilience.  
• Watch out for overfeeding: Fish must eat the food at their own pace. Meat contains a lot of phosphorus, which, if neglected in feeding, insufficient water exchange, and weak filtration, leads to the growth of undesirable algae.  

The Dark Side of Large-Scale Farming: Shrimp and Salmon on Antibiotics

In Conversations Above the Surface, there was also a comparison with commercial large-scale fish and seafood farms intended for human consumption. While in aquaristics, breeders generally strive for maximum naturalness, industrial farming of salmon or shrimp operates purely on the basis of profit maximization and intensive feeding.  

According to Josef Pejša, these large-scale farms are extremely overcrowded, which naturally generates a huge risk of diseases and parasites. To keep the animals alive in circular tanks for shrimp or in cage farms for salmon, the farms are literally "bathed" in antibiotics, regularly vaccinated, and subjected to anti-parasitic baths. Since these are expensive commodities, every single piece is saved through chemical means. The resulting "broilers" fed pellets have very little in common with wild salmon. This is confirmed by experiences from intensive eel or trout farms in Italy and Spain, where artificially fed fish exhibit completely different quality and taste of meat than fish caught in the wild.  

You can listen to the entire interview on the YouTube channel ForAquarist: