A few questions about my tank...

Not knowing how big your tank is, I would say

1. At least 20% a week. I would actually go 30%
2. Below 80 is always better unless you are raising temperature for medical reasons. I stay between 74 to 78, that helps accomidate all my fish.
3. Undoubtedly, a 20g could hold more fish. As to how many more, it would depend on what kind of fish you want. As for what you already have, I like what you got going on with the cories, three is kinda like the minimal amount. I would stay with that unless you are partial to them, then maybe one or two more. Next, the blackskirts. They are a schooling fish, so 6 is kinda a minimum. I would probably go 5, though, to save room, because finally, the guppies. I am not sure if you have male and females, but if you do, they will breed and some extra room is always nice to have. Thats about all I can say off your info...hope that helps.

color doesnt matter with any livebearer. If what I heard is true, guppies can mate with other colored guppies, mollies, platies, etc...

meng-chieh said:

Hi guys,

Just a few questions regarding my fish tank:

1. How much water should I change on a WEEKLY basis; 10%, 20%, or 50%?

2. I have 3 black skirts, 3 guppies, and 3 emerald green cories, what should the tank temperature be? Above or below 80?

3. With a 20 gallon tank, can I get more fish than I already have? How many more?

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I would change 50%. It's what I do, it doesn't hurt fish, or plants, or inverts or bacterial colonies, and my fish are thriving.

I would keep the temperature at 78*F.

Some people may say you can, but Emerald Greens will get fairly large and the blackskirts and cories prefer larger groups. On top of that, guppies do enjoy breeding and filling up tanks. Guppies can only mate with guppies and Endler's Livebearers.

Harlock said:

Guppies can only mate with guppies and Endler's Livebearers.

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Actually, relatively distant crosses within the Poeciliidae do occasionally occur in captivity, but, as one might suspect, such hybrids tend to lack vigor and genetic viability; one such specimen (Poecilia reticulata x Mollienisia sp.) was documented to succumb to a malignant swelling beneath the gill plates.

Well, there you go then. Kissing cousins: didn't work for the Monarchy, nor for your fish...archy.