Smallest organisms with mature females measuring as little as in standard length. This fish, a member of the carp family, has a translucent body and a head unprotected by a skeleton. The one of world's smallest fish based on the minimum size at maturity is "Schindleria brevipinguis" from Australia,their females reach it at 7 mm (0.28 in) and males at 6.5 mm (0.26 in), Males of "S. brevipinguis" have an average standard length of , a gravid female was . This fish, a member of the goby family,its first anal-fin ray further forward, under dorsal-fin 4. Male individuals of the anglerfish species
Smallest organisms "Megaphragma caribea" from Guadeloupe, measuring 170 μm long, is another contender for smallest known insect in the world. Beetles of the tribe Nanosellini are all less than 1 mm long; the smallest confirmed specimen is of "Scydosella musawasensis" at 325 μm long; a few other nanosellines are reportedly smaller, in historical literature, but none of these records have been confirmed using accurate modern tools. These are among the tiniest non-parasitic insects. The western pygmy blue ("Brephidium exilis") is one of the smallest butterflies in the world. The smallest sea cucumber, and also the smallest echinoderm, is "Psammothuria ganapati", a synaptid