Will, the parents are usually killed for food, the Arrowana is a food fish in south america, so the babies w/ yolk sacks are an attempt at saving those fish (for the purpose of getting a few cents), though the vast majority will die anyhow.
I have had silver Arrowanas, and they are amazingly beautiful fish, and i love to sit and watch them, however i have to take an opposing view to Jim.
These are not suitable creatures for a 200 gallon tank, will they be happy there for a few years? yes... but... most people buy as big a tank as they can afford, and rarely upgrade. Silver Arrowanas need a tank on the order of 350 - 500 gallons, they need to be deep front to back, and lengthwise, but not neccissarily top to bottom.
All arrowanas can suffer from a condition called 'gill curve' where the protective skin over the gills curls out and exposes the gills to everything. This condition while, not always life threatening, is obviously not good for the fish and it causes stress. Gill Curl is caused by water conditions, which have to be absolutely pristine. to give you an idea, way back in the day i kept a small arrowana in a planted tank, the plants thrived and sucked EVERYTHING out of the water, no amonia, no nitrate, nothing bad.. but the hard water here in San Antonio was all it took. Someday I hope to keep them again, and I will use 75% RODI and 25% tap.
Finally, big predators make a big mess, a big tank costs a lot, and so do the filters that run them. Arrowanas are awesome fish, but if you are not willing, and absolutely sure your financially capable of supporting this fish through it's entire growth cycle, that includes when it's 4 feet long, then don't get one.
If you do, keep a tight heavy glass lid on your tank, and don't put anything sharp in there like drift wood until the fish is used to you, they are very skittish until they come to recognize patters on activity in their 'home'.
hope that helps.