Apart from the info already given about getting rid of the snails, i am very concerned about your tank.
How big is the tank?
how many fish do you have in total and their species/individual numbers?
Have you tested for water stats?
Are the siamese fighters male or female?
I have a strong feeling your tank is not cycled and i would strongly advise you read up on the articles about it around the forum(check out the beginners section) as i you have not cycled the tank you could be heading for some serious issues in your tank.
If you have 2 male siamese fighters this is extremely bad as they will fight each other to the death once they are released and even having one is bad as male siamese fighters have a tendency to kill and eat guppys, particualy if they are colorful.
Having a male and female siamese fighter is also bad because it is very likely they will fight each other even if they appear to get along with at first, they don't tolerate each other for long.
Depending on the tank size, you could have already overstocked it.
Putting the siamese fighters in breeding nets doesn't make a difference if you aclimatised them properly to the tank as if you want to quarentine te fish you need a spare cycled tank for this.
I would go buy a water testing kit that tests for ammonia/nitrAtes/nitrItes ASAP if you havn't already got one and post us the stats and we'll be able to help you more