My silver sharks have started doing their breeding / breeding dance.
They are only 3"? Isnt that a bit young and small?

if by silver sharks you mean bala sharks then yes they would probably still to too small to mate.

reguardless if they are old enough or not, if you do have bala sharks the there will be no way the will breed anyway. the need a long run for breeding something like 15 feet so unless you have a really big tank breeding probably wont happen.

I am sure that someone will correct me if I'm wrong but I believe that Silver sharks have not been bred in captivity yet.

I have watched videos and read up about the mating of bala sharks and mine match them.

They keep following each other then rubbing up against each other and flicking their tails at the same time against each others, then one goes above the other, then the other goes above that, then they rub against each other some more.

Theyve been doing it for about 2 hours

i have no idea if thats tru or not, but if it is thats really interesting boss

(about them nt being bred in captivity)

just some info i have found dont take my word for it but this was found on the net
quote(It is an Egg scatterer and has been reported to have been bred in the aquarium.)