I have a new 400l tank and want to stock with CA/SA cichlids. I was thinking maybe 3 out of Oscar, green terror, Jack Dempsey, severum, and maybe 6 silver dollars, or some convicts.

Does anyone have any suggestions or advice about this? I have a feeling a may not have enough room for the silver dollars......In which case is there another shoaling type fish that I could add instead?

Also, in terms of cycling the tank, what fish would help with this, and be compatible with the above?

Finally, none of this matters right now, as I can’t go out to buy anything (although I’d love to try to describe this as an essential!) and have never purchased fish online, and not sure whether it’s better to give a small business some trade, or not be encouraging them to go out.

I think I'm best to defer your stocking queries to someone else who may have more experience in those particular fish. However, you may find the various profiles in the following helpful about each species' requirements and compatability:
https://www.fishkeeping.co.uk/modules/ ... aresheets.php?cat=Cichlid https://www.seriouslyfish.com/group/cichlids
https://www.cichlid-forum.com/profiles/

In terms of cycling, you may find this article helpful https://www.fishkeeping.co.uk/articles ... hless-cycling-article.htm - a fishless cycle is much more ethical, less cruel, and means you can fully stock the tank immediately once it's complete. By the time the tank has cycled, hopefully we'll be in a better position to know how the land lies in terms of whether you can go out to purchase fish at that stage - use this time to refine your stocking suggestions.

You might also want to have a play around with some aquarium stocking calculators - you can find these via an internet search.

You're really looking at a bigger tank than that for an oscar - 5ft x 2ft minimum, so I would stick to something a little smaller. Green terrors are extremely aggressive and shouldn't be mixed with other fish (except as a mated pair) in less than about 650 litres. Silver dollars need at least 6ft in length.

That’s a shame as they were my preferences! So I could go severum, Jack Dempsey, and small group of convicts