Short answer: There are far more insects than fish in the world. Context and reasoning:
- Insects are the most diverse group of animals on Earth by far. Estimates commonly cited by scientists place the total number of insect species around 5 to 10 million, with well over a million described so far. When considering individuals, there are countless trillions of individual insects across all habitats. Insects also comprise the vast majority of animal species, often cited as around 80–90% of animal diversity. This breadth of diversity and abundance strongly indicates insects outnumber fish in both species and individuals.
- By comparison, fish represent a much smaller, though still enormous, group. Global estimates of fish species typically range from about 20,000 to 35,000 described species, with ongoing discoveries adding to the count, especially in freshwater systems. The total number of individual fish is vast but not near the scale of insects due to the much smaller global biodiversity and population densities of most fish groups.
Key contrasts:
- Species diversity: insects far exceed fish (millions of insect species described vs. tens of thousands of fish species).
- Population size: insect populations are extraordinarily large overall, with estimates of many trillions of individuals, whereas fish populations, while enormous, are not expected to reach insect-scale abundances across all taxa.
- Habitat breadth: insects occupy nearly every terrestrial and some aquatic niches, contributing to their vast numbers; fish are confined to aquatic environments and fewer ecological slots comparatively.
Bottom line:
- Insects are more numerous and more species-rich than fish, both in terms of species count and likely total individuals, across global ecosystems.
