Notacanthidae

{{Short description|Family of fishes}}

{{Automatic taxobox

| fossil_range = {{Fossil range|Santonian|Recent}}{{FishBase_family|family=Notacanthidae|year=2011|month=June}}

| image = Notacanthus chemnitzii.jpg

| image_caption = Snubnosed spiny eel, Notacanthus chemnitzii

| taxon = Notacanthidae

| authority = Rafinesque, 1810{{cite journal |last1=Van Der Laan |first1=Richard |last2=Eschmeyer |first2=William N. |last3=Fricke |first3=Ronald |title=Family-group names of Recent fishes |journal=Zootaxa |date=11 November 2014 |volume=3882 |issue=1 |pages=1–230 |doi=10.11646/zootaxa.3882.1.1 |pmid=25543675 |doi-access=free }}

| subdivision_ranks = Genera

| subdivision = see text

}}

Notacanthidae, the deep-sea spiny eels, are a family of fishes found worldwide below {{convert|125|m|ft|abbr=on}}, and as deep as {{convert|3500|m|ft|abbr=on}}.

Their bodies are greatly elongated, though more tapered than in true eels. The caudal fin is small or nonexistent, while the anal fin is lengthy, as long as half of the total body length. They feed on animals attached to or living on the sea floor, such as sea anemones, echinoderms, molluscs, and worms.

Although not true eels, these fish do have a similar leptocephalus larval form. However, while the larvae of true eels are about 5–10% of the length of the adult, those of deep-sea spiny eels can grow considerably larger than the adult, and shrink when they develop into their final form. Thus, while adults range from {{convert|20|cm|in|abbr=on}} to {{convert|1.2|m|ft|abbr=on}} in length, larvae of up to {{convert|1.8|m|ft|abbr=on}} have been recorded.{{cite book |editor=Paxton, J.R. |editor2=Eschmeyer, W.N.|author= McCosker, John F.|year=1998|title=Encyclopedia of Fishes|publisher= Academic Press|location=San Diego|page= 86|isbn= 0-12-547665-5}}