Mollies, guppies, crabs, and bottom feeders!

Question
Hello! I have a 10 gallon tank with 6 mollies, 3 guppies (1 male-2 fem), a crab and 2 bottom feeders. I am curious as to if there are too many fish in the tank. Also I would like to know what exactly I need to do in order to assure that my mollies are mating and having babies(if they are males and females--I haven't checked).
   What plants are the best to put in a tank with these diverse fish? My tank is pretty new.

Answer
Good evening Shawnte, I do apologize for my delay in answering your question, I always try to get back to my questioners within a day. I just installed a new power source on my computer after the original one fried in a power surge, so here I am trying to catch up on questions!

Your tank is overstocked, I'm afraid. Mollies grow to be at least 3 inches, sailfin mollies grow up to 6 inches. They would appreciate more swimming room than a 10 gallon can provide, but that doesn't mean people don't keep mollies in their 10 gallon tanks. I would keep only 3 mollies, however, two females and one male since you are interested in raising the molly fry. The guppies are fine in your tank.

The bottom feeders, hmm, what do you mean, exactly? Cories would be okay in there, but any other bottom feeding catfish would be too big for a 10 gallon tank. There are also different kinds of crabs sold in fish stores (including crayfish which aren't really crabs) but I am going to assume that you mean a fiddler crab. Crabs and fish aren't really compatible for many reasons. First, they are actually brackish, meaning they need some salinity in their water. Even kept with other brackish fish, crabs require some land, and without this provision, will weaken and die.

Crabs are usually kept alone in pet stores. It would be best if you could set up a separate habitat for your crab. Take a look at this website for more information:

http://exoticpets.about.com/cs/rarespecies/a/fiddlercrabs.htm

My advice to you would be to either set up another 10 gallon tank, or return all but 2 females and 1 male molly. You'll know soon enough which ones are female! You have virtually nothing to do for them to become pregnant. In fact, a male is not even necessary for several months, since livebearers store males' sperm for up to six months at a time.

Set up another small tank or clear container when you see that your two females are pregnant, and let them release their fry in this separate birthing tank. Large pea gravel or plant cover such as these baby hide-outs (or even bushy plastic plants) will help protect the fry from their moms:

http://www.thatpetplace.com/pet/product/productInfo.web?picGroupKey=10983

Add some aquarium salt at 1 teaspoon per 10 gallons to your aquarium. The mollies and guppies will both appreciate this addition, and this much won't bother your bottom feeders. Salt does not evaporate, so don't keep adding more - just add another replacement teaspoon once you've changed 10 gallons of water. To prevent your mollies from coming down with ich, and to keep your sensitive guppies thriving, you will need to provide high water quality. Change 30% of your water a week with dechlorinated tap water, 15% twice a week would be better. When you test your water with a test kit, make sure there is never any detectable ammonia or nitrite (tests 0 ppm) at any time. The birthing tank will need to be kept especially clean, since fry are even more sensitive to ammonia and nitrite. Nitrates should never exceed 20 ppm.

The mollies can be returned to the main tank after they give birth. Make sure they are well fed (but don't overfeed, so small feedings more often would be best) during and after their pregnancy...although even a well fed molly is prone to eat her fry, if she is not removed soon afterwards!

First rooted plants you could try would be java fern and anubias. Free floating plants such as hornwort and java moss provide excellent cover for the fry, even better than the baby hide-outs I linked to. They also purify the water by absorbing nitrates. Only hardy plants will survive in a system that is consistently salted, but I find (and there is much on the web about this) that mollies are very sensitive to ich if they are not kept in water with some salinity.

Here's an article about salt/brackish tolerant plants:
http://www.wetwebmedia.com/BrackishSubWebIndex/bracplants.htm

From the same site, here's a page on molly reproduction:
http://www.wetwebmedia.com/FWSubWebIndex/mollyreprofaqs.htm

Take a look at wetwebmedia.com and freshaquarium.about.com if you are new to keeping fish and/or plants, there is a wealth of information to be found on both sites. (About.com is out parent site, too.) I hope that helped, feel free to write again anytime, and again my apologies for not being able to get back to you in a more timely fashion, Shawnte.

Take care,
Nicole