will it be okay to put guppies and mollies in the same tank
Yes. Make sure to use aquarium salt because Mollies are more brackish fish, so they will like a lot of salt. The guppies will also tolerate a good amount.
I have 10 mollies and 4 catfish in a 20 gallon tank so do you think its okay to add some guppies as well
The type of catfish makes a big difference here. Mollies can grow a bit and there is a wide variety of catfish. The point is that you may be getting close to the limits of the 20 gallon tank.
The answer also depends upon how much you are willing to perform water changes.
How much do your nitrates increase in between water changes and how much do you change?
I have cory catfish and if I have to I can change the water atleast twice a month
Cory cats really can't tolerate much salt at all. I would avoid it. Mollies can be kept without salt as long as you keep their water quality good and make any salinity changes very gradual.
I keep mollies and corys together in an unsalted tank and it works well overall.
Also, it seems like you are already over your capacity for your 20 gallon. The general rule of thumb is to count an inch of adult fish per gallon. Corys are 2 inches each and Mollys can grow quite big (2-4 inches for black and balloon mollies and up to 5 inches for sailfin and lyretail).
Ah, yes, I completely forgot in my second response that I had mentioned salt in the first one. When you mentioned catfish in the follow up, that should be a red flag for salt, as Anne pointed out.
thanks for the info but the petstore told me to use salt and I did a water change today and added the amount of salt for my tank will the salt kill my catfish...
also mollies and guppies will breed so unless u r wanting to produce more make sure not to mix males and females.
I do want them to breed I had goldfish in the tank at first but I moved them to a 10 gallon and added mollies and platys to my 20 gallon
then u better make sure u only have males or females because they will not only breed with their own but will cross breed as well
NO MORE FISH!!! You already have too many! Mollies get about 3 inches, so that's 30 inches of fish in a tank that maxes at 20. The rule is 1 inch of fish per gallon, but that doesn't really mean 20 1-inch fish in a 20 gallon tank. It's just a limit for whatever kind of fish you buy. Sorry.
one word answer yes! you may get to breed them and make hybrids
This is the third time Jamal please don't post on old topics.