Given A Small Fish Tank: How Can I Take Care Of These Fish?

[mech]

Hello! First off, thanks for any input.
Background: A co-worker is leaving, and she had a small fish tank that needed a home. I adopted them, they were going to be flushed otherwise.
specs: It's not so much a fish tank as it is a bowl: there's no filter or light, and has about half of a gallon of water. There's one live plant, as well. 2 fish, which I can't ID. They look a little bit like mollies, but I'm not sure.
 
I have a couple questions: first off, what kind of fish are these? Second, how can I take care of them? I can't imagine they're doing well in such a small tank. What do they need?
here's a picture of the fish in question.
Thanks in advance!

 

[attibones]

Probably a platy or a molly. Sometimes it can be difficult to tell.

First thing you need: a 20 gallon tank (if they are platy) or a 30 gallon if they are mollies
Second: heater and filter appropriate to size of tank
Third: you'll need to cycle the filter by following the link at the bottom of my sig
Fourth: a liquid test kit featuring ammonia, nitrite, and pH (nitrate is beneficial too, but can be harder to accurately read with some test kits)

In the meantime, see if you can find a large Rubbermaid tub or similar and fill it with fresh dechlor water. Larger volume means less ammonia build up. You'll want to do twice daily water changes or more in the bowl. Once a day water changes in the tub depending on its size. If you can get a heater and filter for the tub, this will help you out while you look around for an appropriate tank.

 

[Lillefishy]

The front one looks like a variatus platy, can't tell what the other is from the pic.
As above you need at least a 20 gallon tank for them.

 

[mech]

ok, thanks for the input! I need a 20-gallon tank for 2 inches of fish? I was under the impression that you could have ~1 inch of fish per gallon, but I might be wrong. I'm really surprised they're alive--the previous owner just replaced their water with tap water. no conditioner, no letting it sit, nothing. They're hardy little buggers, apparently!

 

[attibones]

That rule is really only applicable to only a few species of fish, mostly narrow-bodied fish like the chili rasbora (sort of). There is no real rule for tank stocking. The determining factors include many things like adult size, activity level (platys are fairly active), the amount of waste the adult fish produces (platys are poop machines, as are most live-bearers), its propensity for reproduction (a single female can deliver several clutches of fry off a single mating, clutch sizes vary from 10 to 50+ fry), whether or not the fish needs others of its species (the platy is a social fish, but does not require a true school), as well as many other factors. Before purchasing fish, I like to look at seriouslyfish.com which is a website many of us use. It's got good information about many species of freshwater fish. 
 
If you have a molly (and it is hard to tell from the angle), the molly can reach four or so inches. Both platys and mollies can be a bit bossy, as well, which is another reason for the larger tanks.

 

[PrairieSunflower]

If a 20 gallon tank sounds daunting and expensive, haunt ebay.  I've bought both of my tanks on there for an absolute steal!

 

[attibones]

Or craigslist! I've been eyeing a 55 gallon complete set up for 60 dollars and looking around my tiny apartment wondering "now where can I put you..." Craigslist typically has several really overpriced tanks, but if you hunt enough you'll find someone who really got frustrated with the fish dying (likely because they overstocked it without cycling) and just gave up and is ready to move the tanks on. Those people are the ones to look for.

 

[Ch4rlie]

Lots of good advice given already

 
Don't be put off by us saying that you need a 20 gal tank, do bear in mind this is good for the fish and healthier for them than that little bowl. 
 
As Attibones, already mentioned, Platies do grow to around 4 to 6 cm, depending. And they are active livebearers and do need the swimming space.
 
A little more info about platies that may be of help for you -
 
http/www.fishforums.net/index.php?/topic/46309-platy/
 
http/www.seriouslyfish.com/species/xiphophorus-maculatus/
 
http/www.seriouslyfish.com/species/xiphophorus-variatus/
 
Note - Although Seriously fish website says a 15 gal tank (24 x 12 x 12) would be the minimum sized tank considered, a 20 gal or more is a better option, the bigger the better

 
Not sure if you have kept fish before or not since you are a new member to this site.
 
You will need to consider to get, along the 20 gal tank, a heater and a filter, need not be expensive brands,easily cheeper by purchasing second hand tank equipment on eBay or craiglist as suggested already.
 
Also tap safe de-chlorinator will be needed to make the tap water safe before adding the fresh water to the tank, and lastly, I would recommend you get some water testing kit for ammonia, nitrite, nitrate and pH.
 
Something like these will be fine
 
     [sharedmedia=core:attachments:75833]                        [sharedmedia=core:attachments:75363]
 
 
And the very last point, you will need to cycle the tank to make it safe for the fish to swim in as they produce a lot of ammonia.
 
Ammonia is toxic to fish unfortunately .
 
So you have to cycle the tank to get some bacteria that will consume ammonia in the water to make it safe for the platies.
 
Have a read of this, (the same article Attibone linked earlier in her sig) a Fishless cycle is by far the easiest and quickest method, if you can get some mature filter media and/or some substrate from a friend's or family members fish tank that would give a good jump start to the cycle.
 
http/www.fishforums.net/index.php?/topic/421488-cycling-your-new-fresh-water-tank-read-this-first/
 
In general a fishless cycle takes around 6 - 8 weeks providing you follow the instructions correctly and no major issues during the process
 
 
Do let us know how you get on