Hi and welcome to the forum
How long has the tank been set up for?
What sort of filter is on the tank?
How often and how do you clean the filter?
How often do you do water changes and how much do you change?
Do you gravel clean the substrate when you do a water change?
Do you dechlorinate the new water before adding it to the aquarium?
What are the tank dimensions (length x width x height)?
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What is the
GH (general hardness),
KH (carbonate hardness) and pH of your water supply?
This information can usually be obtained from your water supply company's website (Water Analysis Report) or by telephoning them. If they can't help you, take a glass full of tap water to the local pet shop and get them to test it for you. Write the results down (in numbers) when they do the tests. And ask them what the results are in (eg:
ppm, dGH, or something else).
Depending on what the
GH of your water is, will determine what fish you should keep.
Angelfish, discus, most tetras, most barbs, Bettas, gouramis, rasbora, Corydoras and small species of suckermouth catfish all occur in soft water (
GH below 150ppm) and a pH below 7.0.
Livebearers (guppies, platies, swordtails, mollies), rainbowfish and goldfish occur in medium hard water with a
GH around 200-250ppm and a pH above 7.0.
If you have very hard water (
GH above 300ppm) then look at African Rift Lake cichlids, or use distilled or reverse osmosis water to reduce the
GH and keep fishes from softer water.
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There are several species of molly. The sailfin varieties grow bigger (up to 6 inches) than the more common smaller varieties that regularly grow to 4 inches. The big issue with your current selection of fish is they require different water chemistry. Mollies don't do well in soft water, and tetras don't do well in hard water.
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There are no fish, shrimp or snails that clean up waste. Use a gravel cleaner to suck gunk out when you do a water change each week.
Malaysian trumpet/ livebearing snails are a pain in the butt and breed out of control so avoid them at all costs. Other snails like ramshorn and pond snails can also breed out of control but are easier to find and eradicate. Mystery, assassin and nerite snails aren't much of a problem in aquariums.