Largest fish egg

The largest egg produced by any living fish is that of the whale shark (Rhincodon typus). The largest on record measured 30.5 x 14 x 8.9 centimetres (12 x 5.5 x 3.5 inches) and contained a live embryo 35 centimetres (13.8 inches) long – though it's now believed that this specimen was aborted. It was found on 29 June 1953 by a shrimp trawler in the Gulf of Mexico, south of Port Isabel, Texas, USA.

We now know that the whale shark is an ovoviviparous species – where young begin development in eggs then hatch within the mother's body before being born. This was confirmed by a pregnant female that was captured off Chinese Taipei in July 1995, containing 304 embryos in her uteri. Studied by Joung et al (1996), the embryos ranged in size from 42–64 cm (1 ft 4 in–2 ft) long; those at the smaller end of that spectrum (42–52 cm; 1 ft 4 in–1 ft 8 in) were still within their egg cases, while the more developed embryos had already hatched from their eggs. The size of the egg cases themselves was not documented as part of this study.