Danionella cerebrum – loud as a gunshot!

Small, semi-transparent fish. Head and eye are large; mouth supraterminal. Nostrils well developed. Lateral line canals and pores on head and body absent. Body elongate with a short dorsal fin, situated opposite to posterior half of long anal fin. Tip of dorsal fin situated posterior to a vertical line through tip of anal fin. Caudal fin furcate with remnants of larval-fin fold in front of its dorsal and ventral margins. A remnant of pre-anal larval-fin fold present in adult females, absent in adult males. Anus and genital papilla of mature males located between pelvic fins, at normal position in front of anal fin in females and in immature males between pelvic and anal fins. A window (pseudotympanum) present in body musculature at lateral side of anterior swim bladder chamber, rendering its pigmented surface visible. Scales absent.

Scientists have found that Danionella cerebrum – a tiny fish endemic to Myanmar – 

produces the loudest sound for its size of any fish – over 140 decibels. It does this striking cartilage against its swim bladder
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BBC Video