I came across an interesting article (Microplastic occurrence in fish species from the Iquitos region in Peru, western Amazonia) about a microplastic infection of tropical fish originating in the Amazonus area of Peru. It essentially says all tropical fish were found with the microscopic particles, but carnivorous fish were by far the worst. This may well be because the carnivorous fish retain the microplastics originally ingested by their prey.
What this may mean for our hobby is the fish may develop nutritional deficiencies, become thinner and finally die.
While this study was done from fish found/purchased in a market in Iquitos Peru, most fish were captured by fishermen for sale as food for people, it still represents the present populations of the region. What humans may eat indicated the fish, hobby or otherwise, are affected by the particles.
The contamination of aquatic environments by microplastic has become a major threat to biodiversity. The presence of microplastic is documented in the aquatic fauna of the oceans, but, in the Amazon basin, reports on microplastic occurrence are few. The present study surveyed microplastic occurrence in fishes in an area of the Peruvian Amazon. We sampled 61 specimens of 15 commercial species from local markets in the city of Iquitos, Loreto Department. We detected a total of 2337 microplastic particles, 1096 in the gills and 1241 in the internal organs (esophagus, stomach, intestine, liver, gonads, pancreas, swim bladder and heart). The prevalence of microplastic particles was 100% and the overall average abundance was of 38.3 particles per individual (17.9 particles per individual in gills and 20.3 particles per individual in internal organs). Most particles were found in carnivorous fish. There was no correlation of particle abundance with fish standard length and weight. These results provided evidence of the degree of microplastic contamination of the fish fauna in the region of Iquitos.