How big are baby Betta fish?

Answer 1

When they first develop from the ova and start to wriggle they are about as thick as a hair and around 3 millimeters long. They are best observed with a magnifying glass.

Answer 2

It depends on the species. Wild type Betta Splendens and similar wild Bettas like smaragdina, imbellis and mahachai weigh approximately 1.2 grams

Domestic veiltail and halfmoon Splenden types are around 1.9grams while the new Giant strains of Betta Splendens are 8.8 grams approximately.

The weights will vary from fish to fish as well as depending on when they were fed last so this only a general idea of weight.