They definetly look like a black molly to me.
Black Mollys are the hardest of all molly species to care for.
They really would prefer a brackish water tank, but can be kept in
They need warm water- 76-80F so they need a heater,
and they are one of the larger molly species at 2.5 inches for an
adult male, and 3 for an adult female - and will require a tank of at
least 15G- but a 20G is a whole lot better.
As was said for the swords, they require strong filtration, heat,
and a group.
They absolutely cannot live in anything under 10g- and having kept Mollys
for some time - a 10g is still cutting it too small.
While they are in the bowl, keep them in a very warm room, and do 100% water changes every 3 days, or 50% water changes every day.
They are very sensitive fish, and espescially as fry, should have room to grow. I grow out guppy fry in a 10g tank by themselves, otherwise they are prone to deformities and have to be culled. I dont like culling fish that could have been good otherwise.
My experience would say, the longest these guys can go in the present container, is about 1 week to 2 weeks time. Hopefully they are kept warm enough, otherwise they may die. Try to find them something better, even a tote bin, or plastic container of a 5g size would be immensely better.
What I wonder is - why did you take them if you have no where to put them?
Mollys can live in ponds in Southern California and Florida, but thats about it. My thought is perhaps the neighbor gave them to you to feed to your goldfish?