protecting fry

Question
We have just rekindled an interest in aquariums, and have one devoted to freshwater live breeders, although we do have three zebra danios in the tank for now.  We have only had this tank three and a half weeks. We started with some assorted platys, and added some dwarf mollies a week later.  We were unable to remove the first few fry we saw without stressing them, and we thought they had all died.  However, we are now seeing two colorless fry, and today I saw two black ones. They are too fast, too young  and too skittish for me to guess what they are.  Since they already show black, I am perplexed.  I also have mosquito fish that piggy backed in a load of ghost shrimp, and now I have two female and one male guppy, which I am moving into another tank, but these were all added later. What could produce these little black guys in such a newly established aquarium?

Answer
Hi Linda,
I would think that one of your mollies produced the little black guys.  Mollies may give birth again, and again after spawning only once.  We do not know the male that they spawned with...he could have been black.  This would be the only possible answer.  
When starting a new tank, you must make sure that you have no ammonia, no nitrites, and that nitrates are low, before you add any fish to your tank.  After this, you must add fish slowly, and do 25% water changes every week.  Be careful not to overstock your tank.
Mollies need salt in their water or they will die.  Add one teaspoon of aquarium salt to 5 gallons of water.  The salt will not harm your other fish.  Some mollies finish their lives in salt water, so it is important to add some to your tank.  Dilute the salt before adding it to your water.  When doing water changes, add salt according to the amount of water you removed.
I am against hatcheries or small tanks when fish are pregnant.  Many mollies will die if they do not have the room to swim to release their fry.  Let them swim, and have their babies freely, and let nature take its course.  I know you will lose some, but the fry know that they must hide from their parents.  You will save some, and some will be eaten, but it is better than having the mother die, and have unhealthy fry.
I hope this helps.
Lynda