Betta fish -- compatibility with other fish

Question
QUESTION: Hi,

I wanted to buy a male Betta, and one other fish.  I have read contradictory information about which other fish are compatible with male Bettas.  I would like the other fish to also be colorful/interesting looking (so not as interested in the neon tetras, mollies, danios/minnows, and cory catfish -- read that these 4 are compatible -- well maybe interested in the cory?).  I read mixed things about the fancy goldfish, fancy guppie, swordtail, and the platy -- all of which are more interesting to me -- what is the correct answer regarding these four fish?  Are there others that the male Betta would be compatible with that are also more colorful?

(Sorry, I already bought a 4 gallon heated tank (the Baby biOrb) -- I saw you recommended a 5 gallon -- can't change that now).

Thank you very much for your help!!

ANSWER: Hello,
You cannot put another fish in with the betta except for an African Frog who needs the same water conditions.  Cory fish live in groups, and you would need a bigger tank.  Goldfish also need bigger tanks, and live in cool water.  The Betta is a tropical fish and needs a heated tank.  They also have different water conditions.  The Goldfish needs alkaline water, and the Betta neutral.  There is also the possibility of fish nipping the betta's beautiful skirt.  I'm sorry but 4 gallons is very limited space, and I do not recommend that you add any other fish with the Betta except the African Frog.
Lynda

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QUESTION: PS -- I am thinking about a Platy (male) in the larger 8-gallon tank to go with a male Betta.  Would I need to get more than one Platy (do they need to be in a group)?  If so, how many?  When researching they seemed like they can be in a smaller tank and have some color to them, and are also both tropical fish.  Thanks again.

ANSWER: Hi Cheryl,
It would be best to get a 10 gallon tank.  There is not much difference in the price.  You would need a filter, and let it run on it's own for about 2 weeks, so you will have the right chemistry which is very important.  Before you put any fish in your tank, you must make sure you have zero ammonia, zero nitrites, and low nitrates.  When you have reached the right chemistry, you add one fish, and wait 5-6 days, check your water again.  If your chemistry is right, add two more fish, and wait one week, and add one more. always checking your water before adding another fish.   This is very important as adding all fish at once, your water chemistry would change killing off all the fish.  You can buy these small test kits at your Pet Store, and they are handy to have.
You could then put in 1 betta, 1 male platy, and 2 female platys.  Always put in 2 females with the male as he will harass the females, and one female would get very exhausted.   You could also but in 3 females, and forget about the male as the females are just as colourful at the males.  You could also put in 4 little cat fish, but this would be the limit.   The cory cat fish come in different colours, you can mix them as long as they are not alone.  They are schooling fish, and occupy the bottom of the tank, which is why you could put 4 in your tank.  Feed them with sinking shrimp pellets, and algae wafers, if you decide to put them in your tank.  Water changes every week of 25% is a must.  Check your water weekly to make sure it is right.  This is one of the most important things to do when keeping fish, along with good quality food, and vary the food as mush as possible.
I hope this helps.
Lynda

---------- FOLLOW-UP ----------

QUESTION: Super helpful response, thank you!!!!  :)  You have convinced me . . . I will buy the 10 gallon instead.  

My last two questions -- first one, is about mixing genders -- I don't want baby fish.  Would I have to worry about that if I got the one male Betta, and 3 female Platies?  But sounds like the Betta and Platies are compatible in water conditions, right?  Not interested in the cory cat fish.  Thanks again!

Answer
Hi Cheryl,
The betta, and platies are tropical fish, so they like the same water conditions.  They need a heated tank.  Temperature should be 78 to 80 degrees.  If you do not want fry, it would be best to buy females.  However females that have once been pregnant, can have more fry up to 3 times without the male.  
Also, I want to add, some bettas can be very territorial, and some platies could nip the betta's tail.  This can happen with all fish, so watch them closely in the beginning to make sure they are doing fine.  The betta's long skirt is an attraction.  I have bettas with platies, and never had this problem, but it can happen.  It always depends on the fish.  I just wanted to mention this.  Also adding silk plants, and hiding places in your tank would help.
I hope all goes well, enjoy your new tank!
Lynda