Very new to fishkeeping, and I need help!!

[newbiefish0329]

Hi there, I am very new to fishkeeping, and I have lots of questions!!!
Here's what I have:
one of those split tiny betta tanks (don't judge, they are my kid's fishies):has two bettas in it
a 46g bow front freshwater tank that was started on 7/19:has 3 fish and 2 tiny catfish (I am such the newbie that I don't even know what kind of fish they are.. I will pay more attention when the fish store guy gives them to me, LOL)
a 10g tank with a broken filter, with one pregnant neon tetra in it..

I really truly don't know what I am doing.. I need so much advice, and I have so many questions...

1) do I replace the 10g tank now that the filter is broken? The filter came with the tank and isn't replaceable.
2) Can I keep the pregnant fish in that tank? What do I do once she has babies? What do I do with the babies?
3) The other fish that was in the tank with the pregnant fish was moved to the big fish tank (stupid move), and died this morning. I saw the catfish eating him! What do I do with the big tank now? Do I change the water? Do I just condition it again?
4) I have only had fish in the big tank for a week or so, so I don't think the tank has fully 'cycled'. When do I change the water? And to what degree, 10%, 25%, gravel vaccuum?

Please, let me know what I should do.
Thanks!!
Dara

[LyndaB]

Welcome to the forum.

First things first, you MUST read this: I just learned about cycling but I already have fish. What now?! - Aquarium Advice

You've got a couple of issues going on here. It seems you understand that you need filtered tanks, but I get the feeling you don't really understand what "cycling" a tank entails. The link will help you see what's going on and what you need to do.

I highly suggest you go on-line and order yourself an API master kit. You can get this for less than $20. If you're in the US, I recommend Kensfish.com. He has them for about $17 and has great customer service. It's very important to find out your water parameters for ammonia, nitrite, nitrate and pH.

Since you have fish, depending on the parameters, you may need to do daily water changes. The ammonia and nitrite will make the water toxic.

What size tank is the split betta? They really do best in 5 gallons minimum. They need a filter and a heater, too.

It's vitally important to know what species you have. You need to find out what those catfish are. The various species have different needs and schooling requirements. Some will also outgrow your tank. Don't trust the lfs to tell you what the fish is, prior to purchase you should be doing your own research.

If you've got fish in the 10 gallon then yes, you need to replace the filter. The pregnant fish can stay in there and you can use that tank as a grow out tank for the fry, if you wish. That said, I keep my fish in the community tank when they give birth. I have plant coverage for the fry, so I don't have to be bothered with grow out tanks.

[Bettafanatic]

It's very irresponsible to have fish if you haven't done your research first. If you fail to prepare, then prepare to fail. Those Betta fish need to be moved ASAP. The neon tetras need schools of six or more or they will get stressed. Do a whole lot of research on fish keeping.

[Samzter]

Welcome to AA! Others have suggested what to do with your fish, just thought I'd point out that neon tetras dont get pregnant, but they carry eggs. It really needs to be in schools of 6+ but don't do that if your filter is broken and your not cycled. You may want to look up dropsy or internal parasites just to double check that she's carrying eggs and not ill