How many fish for 85litre tank?

[ElizabethW]

BTW, Myriophyllum spicatum is a noxious weed and banned in some countries. It has been introduced everywhere (except Antarctica and Australia I believe) and proven dangerous to the native species, hence the ban. Don't know where you live but you might want to check this.

A weed is something that grows where you do not want it. Any plant can be called a weed.

Myriophyllum spicatum is not classed as an invasive (what I think you mean) species here. It cannot survive in the wild. It must have aquarium conditions and temperatures much higher than are natural.
Myriophyllum aquaticim is an invasive species, but that's not what I have.

This is why we use latin names in my line of work; to avoid confusion.

 

[Byron]

A weed is something that grows where you do not want it. Any plant can be called a weed.

Myriophyllum spicatum is not classed as an invasive (what I think you mean) species here. It cannot survive in the wild. It must have aquarium conditions and temperatures much higher than are natural.
Myriophyllum aquaticim is an invasive species, but that's not what I have.

This is why we use latin names in my line of work; to avoid confusion.

Myriophyllum spicatum is classified as a noxious weed in some states, as a weed in others, invasive banned in others, or prohibited in still others. Here is the USDA site, click on "legal status." Not knowing where you live, you c an sort this out. My original post was accurate.

http://plants.usda.gov/core/profile?symbol=MYSP2

 

[Rapido17]

You are absolutely right! I do not want to breed the guppies! This might change in the future but since I am just starting out I think I will err on the side of caution and go for all males. Would five or six be okay?

This might seem like a silly question, but when doing water changes, how do I stop the temperature of the tank going down? Right now it doesn't really matter since I have no fish, but the temperature of the water drops 2/3 degrees when I do my water change and takes a couple of hours to return to normal. Is there something I should be doing to prevent this?

When I do a water change to my tank I siphon out the required amount of water and then take the temperature of the water remaining in the tank. I then add the freshly treated water at the same temperature as that still in the tank. Job done and no shock to the fish.

 

[StandbySetting]

Regarding nitrate - 20ppm is fine, I read in this thread somewhere that 40ppm is considered dangerous (source?) - hobby test kits are woefully inaccurate, not only that a paper I read a few years ago tested the long term effects of elevated nitrate levels on a range of fish, I can't for the life of me find it, obviously as low as possible is best but we have to be realistic, personally I'd regard anything under 50ppm as acceptable given that the fish in the study were subjected to levels of 400ppm with minimal long term issues. Obviously it will vary from species to species, your bread and butter fish are going to be much more tolerant than some wild caught discus...