What’s the significance of fish from the Rivulidae family in freshwater ecosystems?

Killifish are omnivorous fish with a preference for a carnivorous diet in the environments where they occur, and can feed on small organic matter debris and aquatic invertebrates. For this reason, in nature they act as biological controllers, capable of reducing infestation rates of eggs and larvae of species of mosquitoes that transmit contagious diseases, as well as combating the proliferation of different pests and other pathogens.

What are some of the challenges in the conservation of these animals?

Because these animals live in microhabitats, they are threatened by several problems. However, they are very common in private properties such as farms, large houses and even large plots of land in cities. This is one of the biggest challenges for their conservation, as many owners destroy their microhabitats, judging them to be dirty and without any productive potential. However, these locations are monitored annually by PAN… [The National Action Plan (PAN) of the Chico Mendes Institute for Biodiversity Conservation (ICMBio) which aims to protect and preserve fish from the Rivulidae family… and in conjunction with this monitoring, there is an environmental education work with the owners to make these people aware that these microhabitats, are not actually a problem; they contain life and species that are critically endangered. Our work consists of making these people understand that in nature everything is important and interconnected. Therefore, a Pantera onca is no more important than a killifish because the richness of fauna and flora in those environments is connected to an entire chain of organisms. Another problem that is illegal wildlife trade…

How does the illegal wildlife trade affect their populations?

The aquarium hobby market generates a lot of money. In Brazil, for example, fish rank third among the most traded animals, with dogs and cats coming first. It is a hobby practiced by many people. And in other countries they may even rank first. For this reason, some aquarists are fascinated by Rivulidae’s fish life cycle and want to obtain these animals. These people acquire the eggs of these fish through smuggling and have contact with other people who also breed them through clandestine groups. From this, they exchange information about the reproduction and maintenance of the fish. They even exchange species through eggs, which unfortunately facilitates smuggling, so that the animals have genetic viability. But many also act directly in the puddles, capturing adult individuals using information passed on by the clandestine groups.

In conclusion, killifish, or, “cloud fish,” are vital components of freshwater ecosystems, but the general population is often unaware of their significance. These small fish utilize a unique survival strategy called diapause, allowing their eggs to remain dormant during dry seasons and hatch when rains return. However, climate change and human activities like habitat destruction and illegal wildlife trade threaten their existence. The public must be aware of the importance of these species and the impact of illegal trade. Before acquiring any exotic animals, always check the IUCN’s red list to ensure they are not endangered. By raising awareness and making informed decisions, we can protect our fauna and maintain the delicate balance of our ecosystems, preserving both biodiversity and cultural heritage.

Cover image: Temporary puddle located in the northern region of Minas Gerais, Brazil. Davi Hinncands de Oliveira, March 2023.

Preview image and figure 1: Male individual of Hypsolebias janaubensis (Davi Hincannds de Oliveira. Pirassununga, 2023).