i have a 10 gal tank with 4 male guppies 5 female mollies 1 plecostomus and 2 fry

actually im a she not a he lol. I dont know i bought it from walmart. I know people that have had them in 10 gallons and did fine. im just saying if it gets to big i can give it away easy.

The more plants the better for fry. If you can, get some thick java moss or willow moss, or both, and perhaps some crystalwort(I recently discovered crystalwort is AWESOME when you want fry, it's a top floating plant unless you can get it to stick to something, and if you pen it it can get thick up top and babies can get in and on top where adults have a lot of trouble getting them. Grows fast, quite fast, provides hiding and food. And by pen I mean a tube up top to keep it from getting blown around or sucked into the filter, but not cut off from the tank itself if you know what I mean). Good stuff, hard to have too many plants when you have babies in the mix.

Also...Yeah, mollies don't go well in a ten gallon tank. Because of their size, bioload, and tempers, as well as their love for a group, it's just a bad idea to have them in anything smaller than 20 gallons as a bare minimum. Nothing fine about that and unfortunately once you have a problem it will be too late and it's highly likely you will lose the entire tank to whatever illness pops up due to the stress and bioload which will be extremely difficult to maintain safely.

And it's not just their size and water needs, but their bioload is quite large. So is a plecos...from what I can tell, you have nice young common pleco. He will not do fine in there and there is no possible way for him to do so. People you knew who had plecos in smaller tanks likely had smaller type plecos, or ones that died well before their time and those people did not know it wasn't normal...or they sent you fibs. He will get longer than that tank, and since he can't, he will stunt and his organs will eventually be crushed, slowly and very painfully, by his stunted body. People say that fish wont out-grow their tank and it's fine, but they neglect to mention that organs do not stop growing because the body does. They can live many years(twenty to thirty if well cared for, maybe more), and that wont happen in a small tank, he will have a very long, excruciating death if you keep him in there. If it's been a few months stunting will likely set in soon if it hasn't, and it doesn't look like it has just yet so you still have time to move him or find a new home for him.

Having babies in the mix will hurt the bioload even more. You beneficial bacteria and cleaning will have a very hard, if not impossible time keeping up. I'm sure it can be done for a time, but not permanently. There will be filth, more likely to have parasites and nasties, and likely aggression later. Mollies are prone to aggression when cramped, and they can do some major, sometimes fatal damage to other fish.

Just because petshops keep them in trashy conditions doesn't mean they can survive it long and that others should do it too. Even in petshops where they usually sell most of their stock within a week, some still die due to the poor conditions and lack of space. I'd give you maybe a year, year and a half(could very well be less, stress really messes up the immune system and it doesn't take much for a nasty to strike and get stronger then), with -very- good care before trouble hits and the tank is destroyed by a parasite or disease.

It's not worth it, trust me. =( I did that with my first platy tank not knowing better, six platies in a ten gallon tank, year and a half later even with a lot of extra care: boom, the stress was too much and allowed a nasty to take effect on one fish, which then passed to the rest and killed them within a day. NASTY parasite called ich, which is in most home aquaria as is...Because of their trashed immune systems from stress and lack of space, it took hold very fast, bred, spread and killed quickly. Small normal amounts of ich are often harmless to strong healthy fish, but not to ones with stress and messed up immune systems. Stress hurts the slime coat which protects them from such infections and infestations. Without it they become a breeding ground allowing the nasties to multiply to a point even your healthy fish will be at risk.

If you want that set up, minus the pleco, I'd get yourself a nice thirty gallon tank. If you want the pleco, their minimum tank size is 55 gallons, but they prefer 75 gallons because they can get a foot and a half long, some closer to two feet long(and obviously a three foot long tank isn't going to be comfy).

You can do five guppies in there ok though. Better with endlers for space, but guppies will do alright.

On another note...dwarf plecos, like the zebra, they get about two inches long, but they love space. It's not recommended to keep them in anything smaller than 30 gallons. This I only know from research because I wanted one...but they're expensive and hard to find...so I have no personal experience to share, sorry. =( Smaller plecos like the rubber-lips will do ok in a 20-30 gallon tank though, but not a ten gallon.

Well, I don't know about you but, if I don't have space for the fish I normally don't get them. I mean I want oscars, a dinosaur bichir and goldfish, but my tanks are tropical and too small or full of fish an oscar or bichir would love to eat. I do however, have occasional...people who shall never be spoken to again...send me "Surprises" for my tanks, and if I absolutely do not have space for them, they either go to a friend with the space, or a petshop. lol

Advice given. It's up to you to listen or not. Your pleco has the potential to live a few decades, your livebearers all have the chance to live for five or so years if well cared for. But they wont last long here. Many think those fish only live a year or two as normal, nope. They can live quite a few years.

Got your plant info. A lot of users gave some good ideas that I, too, may steal if I can find all the plants. Always looking for new plants in my tanks. More plants, more hiding, food, oxygen, tad extra filtration and security, happy days. :3