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EveryFish

Data deficient or not assessed

Too little is known to judge. 17 fish on EveryFish so far.

Data Deficient is the IUCN Red List category for species that have been assessed but for which there is too little information to judge the risk of extinction. It is not a statement that a species is safe. Many fish fall here or have never been assessed at all, especially those of tropical rivers, the deep sea and poorly surveyed coasts. Some well-known fish are Data Deficient because their numbers are hard to count.

Too little known

The arapaima of the Amazon is listed as Data Deficient: it has been overfished in many areas but has recovered under community management in others, and it is hard to count across such a vast basin. The common sole of Europe, one of the most valuable flatfish, and the giant grouper of the Indo-Pacific are also listed as Data Deficient. Many small fish of India's rivers and wells, such as the blind catfish of Kerala's aquifers, are known from only a few specimens.

Not assessed

Of the more than 36,000 known fish species, many have never been assessed by the IUCN, and others have assessments more than ten years old. Species described recently, such as many cave fish and deep-sea fish, often have no assessment at all. EveryFish groups these under Data Deficient or not assessed. Scientists use surveys, environmental DNA and catch records to fill the gaps, and some Data Deficient fish turn out to be threatened once they are studied.

Famous data deficient or not assessed fish

ArapaimaHard to count across the AmazonGiant grouperA huge Indo-Pacific grouper

Still to be written: Common sole, Bighead carp, Horaglanis krishnai.

Further reading

GroupSharkRayCarpCatfishSalmonidHerringCodTunaPerch-likeCichlidReef fishEelFlatfishLivebearerAncientOther
WaterRivers and lakesEstuaries and mangrovesCoasts and shelvesCoral reefsOpen oceanDeep seaPolar and cold seasCaves and springsBetween sea and river
UseFood fishFarmedAquarium fishSport fishingCulture and faithVenomous or dangerousInvasiveScience and research
OrderBest knownA to ZOldest firstNewest firstBy size
WorldSeahorse Small marine fish with horse-like heads and curled tails in the genus Hippocampus.Other · Coasts and shelves 🇧🇷 Brazil and 4 moreHoplias aimara A large freshwater predator from South America known for its size and mercury accumulation.Other · Rivers and lakes · 1846 🇧🇷 Brazil and 4 moreArapaima Giant air-breathing freshwater fish of the AmazonOther · Rivers and lakes · 1822 WorldOarfish Extremely long pelagic fish known for their ribbon-like bodies and association with sea serpent myths.Other · Open ocean · 1772

Photo credits on this page

The small pictures above come from Wikimedia Commons under free licences. Some are cropped to fit.

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