Preparing first tank

[JxsPxxle]

Thank you for your reply. I have picked up a testing kit. The dwarf puffers look lovely but I only have a 40l and am thinking of some harlequin rasboras, guppies and otocinclis at the moment (with my hitchhiker snails )

Sounds good! Make sure your harlequin rasboras are in a group of at least 10 and I would hang back on the otocinculus until your tank is established and algae growth begins because this is what they will be feeding on.

 

[JxsPxxle]

Thank you for your reply. I have picked up a testing kit. The dwarf puffers look lovely but I only have a 40l and am thinking of some harlequin rasboras, guppies and otocinclis at the moment (with my hitchhiker snails )

Sounds good! Make sure your rasboras are in a group of at least 10 as they are only little guys and I would hang back on the Otocinclis until your tank begins algae growth as, other than maybe algae tablets this is their source of food. Guppies are wonderful fish just remember they are live bearers so take into consideration the male and female ratio.

 

[Essjay]

I only have a 40l and am thinking of some harlequin rasboras, guppies and otocinclis at the moment

I'm afraid there are some problems with this proposed stocking.

Harlequins and otos are soft water fish while guppies are hard water fish. Depending on the hardness of your tap water, one or other will not be happy. Look on your water provider's website for hardness. If they give it you need a number and the unit of measurement rather than some vague words. If they don't, take some tap water to a fish store and ask them to test GH. Make sure they give you a number.


Harlequin rasboras do need a bigger tank than 40 litres (10 gallons) I'm afraid. They need a tank with a 60 x 30 cm footprint (24 x 12 inches). https://www.seriouslyfish.com/species/trigonostigma-heteromorpha/
Otocinclus need to be in a shoal but it is unlikely that a 40 litre tank will be able to grow enough algae to feed 5 or more otocinclus.


If your water is hard, male only guppies are fine in 40 litres; or an alternative would be male only endlers. No females or the tank would be very overstocked very quickly.
If your water is soft, one of the smaller tetras such as ember tetras, or one of the Boraras species such as chili rasboras would work.


Sorry to totally trash your fish wish list, but it is better to find out now rather than after you've bought them.



EDIT:
After typing all that, I saw you are in Norwich so I looked on Anglian Water's website. Using the postcode for the Spar shop in Aylsham Road, the website says your water is very hard - 328 ppm and 18.6 dH.
This is much too hard for harlequins and otos, I'm afraid. With a small tank of 40 litres (10 gallons), the only suitable fish I can think of are guppies and endlers. Other members may know of other hard water fish suitable for small tanks.