Hi guys.

I have just purchased a aquarium starter set. All the tank, stand, filter, heater included. I have put all the gravel, decor and water in and have treated the water. The shop told me i have to wait a week now before i can add fish.

So as a starter what would be the best type of fish to go with? I want to get it right with smaller ones first before i go buying larger more expensive fish. And also make sure i don't ene up buying ones that will attack the other fish.

Thanks for any advice.

Waiting a day , a week or a year will not "cycle " a tank and make the conditions suitable for adding fish .
"Cycling" a tank means building up a colony of bacteria that will break down the fish waste so that it does not "poison " the water and leave the fish dead or with gill damage .
If you google "fishless cycling " you will get instructions on how to do this ...... you can even buy chemical kits to make it easier I believe.

Most beginners will however just add a few fish and hope for the best and sometimes all the fish will survive and appear to be fine but will have suffered during the process .
Think of an asthmatic in a very smokey atmosphere - it probably wont kill them but their breathing will be awful until the air clears.

Once you are ready to add fish the size of your tank will have a bearing on your choice .
How big (dimensions or capacity are fine ) is this tank ?

If the tank is under 60cm by 30 cm (length by width ) or approx 65 litres or less then I would choose small fish like cherry barbs , glowlight tetras , small coydoras for example.

The tank is 60 litres.

small fish then, tetras, barbs, danios etc. just need to make sure that the species you introduce are compatible.
i.e. barbs are fin nippers - don't have these with male guppies, or any other fish with long, flowing fins.

a small group cardinal tetras in a well planted aquarium looks absolutely stunning.
this is what i'm going to do next time around, at the moment i'm letting my stock live out their lives (as they're so mixed) before re-stocking, hopefully with cardinals.

i've got an albino red tailed shark in my 60 litre, he's the biggest fish in there by far and cohabits with a handful of mixed tetras as mentioned above (they're mostly what i've taken from other people when they're getting rid of their tanks)

i've had him in there with at most, about 14 other small fish and to be honest - i think i was pushing it then. i wouldn't have that many again.

however, he's happy and healthy (he may actually be a she, but...)
and he's been going for about 5 years now. has a plant pot which he seems to have claimed as his own and chases the other fish out of there.

when i started with it, i didn't do a fishless cycle, i wouldn't do it again.
bringing fish home then losing two in the first week when it's fully avoidable isn't really a nice feeling. but in the pet shop trade, it's generally regarded as "acceptable" to do this.
i was given the same advice as you - to wait a few days for the silt from my gravel to settle and then get a couple of fish to start it off, with a week at least between adding more fish.

I have a RTBS and find him a good indicator of tank conditions, if anything happens with my water or i miss a water change, i know pretty quickly because my shark changes colour to show he's miserable!

No idea why pet shops give out such crap advise regarding fish tanks, although it's probably because telling people who are buying a tank to wait up to a month to cycle it would probably put a lot of them off.

I cycled my first tank the hard way and lost a few fish, purely out of ignorance.

Anyway, back to the OP

my first tank was 60l and you can get some very nice fish for a small tank like that, small shoal fish like cardinal or glowlight tetra, then after a month or so when the tank has cycled and no more fish die you could move onto slightly more expensive fish such as corydora catfish

when you get more confidence with your tank you can get small cichlids such as Rams, which are very colourful and quite timid

one thing to note, if you bought a starter set your filter will probably be crap and underpowerer, take it out and buy a decent internal one.