Part 1 (20 minutes): Simple introduction — What is new and why is it important?
Imagine livestock keeping as a cupboard with different compartments for different animals. Cattle and pigs have long been the large doors of this cupboard; poultry and small livestock came later. In recent decades two new compartments have clearly grown: one for fish in aquaculture and one for insects in breeding facilities. Aquaculture operations are businesses that deliberately keep, breed and harvest fish, shellfish or crustaceans. Insect farms produce insects or insect products either as food for humans or as feed for animals. Both areas are important because they contribute to food supply; farmed fish make up a significant and growing share of the fish produced worldwide for human consumption (see FAO, SOFIA 2022), and insects are increasingly discussed as an alternative protein source (see FAO 2013).
Species-appropriate husbandry generally means that an animal's needs are taken into account as far as possible: the ability to show species-typical behaviour, protection from pain and stress, appropriate nutrition and health. For fish this can be simply imagined like a good pond: clean water, enough space to swim, feed suitable for the species, and protection from disease. For insects one imagines many small "apartments" or containers in which temperature, humidity and feed are managed so that the insects can develop. Both images are useful, but the details differ considerably.
A practical comparison helps: if you care for a creature in an aquarium or an ant farm set, you quickly notice that water quality, space and feeding are important. In industrial practice additional aspects come into play: large numbers, economic constraints and legal requirements. This combination creates challenges for animal welfare, because mistakes in water chemistry, high stocking density or improper killing methods can quickly affect many animals.
Important: For fish welfare there is a growing scientific basis on which concrete recommendations are possible; for insects research in many areas is still developing, and in fundamental questions such as sentience of many insect species there are justified uncertainties (see EFSA 2015; FAO 2013).
Part 2 (20 minutes): Deeper dive — Technical terms and concrete aspects
To assess species-appropriate husbandry, experts use some central terms. "Stocking density" describes how many animals are kept per unit of area or volume; for fish the indication is often in kilograms of biomass per cubic meter (or per square meter), because water and oxygen are limiting. "Water quality" includes parameters such as dissolved oxygen, temperature, pH, ammonia/nitrite/NOx concentrations and visibility; these parameters affect stress, growth and disease susceptibility of fish (see reviews on aquaculture, FAO SOFIA 2022).
Another important term is "species-related behavioural needs": these are behavioural patterns that frequently occur in wild conspecifics and whose suppression promotes stress or poor health. For many fish species swimming, fin movements, foraging and social interactions belong to this. In breeding facilities simple measures such as structuring the tank bottom, variations in current fields or visual barriers for social groups can help meet these needs; empirical studies on the effectiveness of such measures are discussed in review articles (e.g., Huntingford et al. 2006; Ashley 2007).
In fish welfare research the topic of "pain perception and stress" is central. Biologists speak of "nociception" when an organism detects damaging stimuli, and of "sentience" or pain when this results in subjective suffering. The scientific debate has yielded convincing findings for many bony fish and some other fish groups that suggest fish process stimuli not only reflexively but also show avoidance behaviour and long-term changes (Huntingford et al. 2006; Ashley 2007). These findings influence recommendations for handling, stunning and killing at slaughter. At the European level Regulation (EC) No 1099/2009 governs the protection of animals at the time of killing and in principle requires stunning before killing for vertebrates, which includes fish.
For insects central technical terms are temperature regime, humidity, stocking density and developmental stages (larva, pupa, imago). Because insects have very different biologies, species- or species-group-specific standards are needed. The FAO review on edible insects (van Huis et al., FAO 2013) describes how different species have different requirements for temperature and humidity and how this affects growth and mortality. A particular challenge is the assessment of suffering: unlike fish, the data on pain perception in insects are much more incomplete; expert panels consider the evidence to be insufficient and variable across species, which is why management and killing practices should be guided by the precautionary principle (see EFSA 2015).
Regarding killing methods, for fish there are practicable, scientifically studied procedures such as percussive stunning, electrical stunning or combined methods, with documented effects on stress indicators and time to death; corresponding regulations and recommendations are found in EU provisions and the specialist literature (see Regulation 1099/2009). For insects the practical methods are diverse (heating, freezing, CO2 treatment, mechanical destruction), but systematic comparisons regarding possible suffering during killing are often lacking or available only for individual species (EFSA 2015). Therefore it is recommended to choose methods that act quickly and minimize suffering, and to use only methods that are technically appropriate for the species and production scale.
Finally, legislation plays a role. In Germany and many other countries the Animal Protection Act (TierSchG) applies, which contains general duties to avoid pain and suffering; this law is practically supplemented by professional guidelines and technical standards. For the marketing of insects as food, the EU's novel food regulation (Regulation (EU) 2015/2283) is also relevant, since many insect products are legally considered novel foods and must therefore undergo approval procedures. This has implications for production standards, hygiene and labeling.
Part 3 (10 minutes): Applications, limits and small thought exercises
Concrete applications: An aquaculture operation that wants to work in a species-appropriate way continuously monitors oxygen, temperature and ammonia; it pays attention to appropriate stocking densities and plans procedures for disease prevention, vaccination or other veterinary measures; when killing it chooses recognized stunning and slaughter methods for the respective fish species. An insect breeder selects species-appropriate temperature and humidity settings, optimizes feeding according to the developmental stage and chooses a killing method that is quick and technically reliable. In both cases biosecurity and hygiene are important because close housing conditions can promote the spread of pathogens (FAO SOFIA 2022; FAO 2013).
Limits and uncertainties: Scientifically solid data on the welfare of individual fish species are not available for all species in aquaculture; especially for newly introduced species extrapolations are often necessary. For insects there is a larger data gap regarding the extent to which many species experience pain or suffering, and regarding the effectiveness of various killing methods across many species (EFSA 2015). Economic pressures and scale effects can hinder practical implementation of species-appropriate practices; therefore legal minimum standards must be complemented by research and technological development.
Small thought exercise 1: You operate a small school aquaculture with a fish species of your choice. Name three water quality measurements that you would check daily and briefly explain why.
Small thought exercise 2: Assume an insect species intended as a food source requires high air humidity for good growth. What risks arise for animal welfare and hygiene, and what measures could you propose to reduce these risks?
For both tasks: justify your answers with the goal of reducing stress, protecting health and avoiding unnecessary suffering. If possible, search in libraries or on the mentioned websites for concrete values or recommendations; note that different species require different numbers and many reviews provide only general guidance (see sources).