Inbreeding, should I be concerned?

I'm a beginner to my fresh water aquarium, so I apologize for my rookie questions.

Just in case, here's my tank info/history:

I have a 16 gallon tank with four Mollies, 2 Dalmations & 2 Black.

Before putting any fish in, I did a fishless cycle which took about 4.5 weeks to complete before any ammonia was properly destroyed within a 24 hour period. After the cycle I put in 2 mollies, then the other 2 about two weeks later.

Each set of Mollies has a male and female. And if at the time I knew what I know today, I would have kept it to one male for the entire tank.

One of the females came pregnant, but I didn't know it at the time. She gave birth about a week ago, maybe 10 days ago. I took out as many of the fry as I could. I have 15 of them in a external breeder tank. The kind you hang on the side of your tank and it uses an air hose to force water through it for filtration and circulation.

I figured at this point, if they're still around there's a good chance they'll survive. I called a few LFS to arrange for dropping off the young ones after they're close to 1" long, which I plan on doing.

So here are my questions:
If I wanted to keep one of them, and as much as Mollies procreate, should I be worried about inbreeding causing issues?

I'm feeding my adult Mollies Omega One MinI Pellets and the fry New Life Spectrum Grow fry starter. At what point do I switch the fry to something other then the fry starter?

Thanks!
Jason

 

I can't help with the breeding, but mollies can reach up to 5" which is too big for your tank.

 

5"? Is that accurate? That's a lot bigger then what I've read. If that's the case, I have no more room to add another and I'm probably going to be over crowded when my 4 are full grown.

 

Shortfinned Mollies max out around 3.5", and Sailfins get to 6". There are species of Mollies that get 5", but they are not the two common varieties in the hobby.

As for inbreeding: no, it is not a concern. That is something that people assume because it is a problem with Mammals, but it is not a serious concern with fish.

 

16 gallons is indeed too small for mollies. Size aside, they are very active and need lots of space. They also have a large bioload and create too much waste for that size tank. I keep 4 in my 29 gallon and would not go smaller.

Inbreeding is very common in mollies and most breeders do this intentionally. From my understanding some fish are more affected by it than others (for example, guppies with crooked spines), but mollies not so much. Line breeding by mating daughters back to their fathers is common practice and it guarentees colors and other desirable traits. So nope, you don't have to worry about that.

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