Bettas are slow retiring fish. They do not move around much normally. Silvery coloured "pectoral fins" are quite common.
The "ventrals" is simply another name for the fishes "ventral fins" These are the paired fins in front of the Vent (aka Anus).
you can tell if its a boy or girl by the fins the male Betta has long fins and the female Betta has small fins
A female betta has very small fins with a long body while the male betta have lots of nice flowing fins.
Male betta's are larger, more colorful, and have much longer fins. Female betta's are small, less colorful, and have short stubby fins.
gold fish have 7 fins
usually a male has longer tail fins but they are about the same for side fins
Male betas are colorful and have large fins. Females have virtually no fins and have no color
There are two sets of "paired" fins. The ones on each side of the fish behind the gills are the "Pectoral Fins" and the ones in front of the fishes vent on the underside of the fish are the "Ventral Fins". Sometimes these fins are wrongly refered to as "Pelvic Fins".
no fish are animals that have only 2 fins
Correct
Thats how they swim
Your betta fish is a female if she has smaller fins than an average male.