Need Some Stocking Suggestions

I have a 35L fish tank, which I have had for nearly 6 months now, I cycled it all and then got my 2 corydora catfish and 1 dwarf gourami and 2 platy's. Everythink seemed to be going well except my one catfish died but since then everything had been fine until 3 weeks ago and I went out for the night came back home and found my gourami and one platy sunk dead on the bottom. I scooped then out and went to bed wondering what could have happened when I woke up I found that my other platy has floating on the top so I did a full water change and scrubbed out the whole tank. Since then my catfish was VERY ill for about 3 days but then was fine. I think somehow when I sprayed my perfume some must have gotten into the tank as I had the water tested and I did nothing else out of the ordinary. But now my catfish is lonely and I need to get him so fishy friends. He has been fine for just over 2 weeks now so I am sure he is ready. I was thinking about getting him another peppered catfish friend and maybe 5 guppies. Do you think the guppies are a good idea as I have never kept them before? I just need your opinions on my idea for stocking the tank or some of your suggestions for stocking The picture is of my tank when I set it up about 6 months ago before I got any fish, I have more hiding places now (plastic logs and pebbles) and have planted some real plants now 

The perfume might have caused it. If you scrubbed the tank down and left the filter dry, i'm afraid the cycle most likely broke and you need to do the whole thing over again.

oh thanks for the advice anyway, will I have to do it even though my catfish has been living in it for nearly 3 weeks since I did the big clean ? If I do need to re-cycle it do you have any suggestions to what fish I could add with my cat fish after i have done that? thank you so much in advance for your help

How did you cycle the tank? When you did the big clean what did you do with the filter media? If your catfish is a peppered cory and not a salt & pepper cory then unfortunately this tank is too small for it, so I would return him.
 
What are the dimensions of the tank? Is your water soft or hard?

Um he is a peppered catfish but my uncle, he is the manager of my local fish shop, said that they grow to about 2 inches the boys can get to 2.5 inches. When I cycled the tank I bought my tank, washed it out washed all my ornaments and gravel and filled the tank with water, I bought a few test kits and tested the water every other day for a week and every time my my pH was 7 (green) and my nitrite and nitrate were yellow. When I did the big clean I took the filter apart (dont worry I do this most times that I clean the tank and thats almost weekly so I know what goes where when i put it back together) and I cleaned all the filter parts and washed them out then I put them back together and put it back in the tank. My water is fairly soft I think

My tank is about 50cm long 25cm wide and 28cm tall not including the lid and it can hold 35L Any ideas what fish I could add in with my catfish?

What did you wash your filter in?
Check this link to see what size tank the pepper cory should be in: http/www.seriouslyfish.com/species/corydoras-paleatus/ The tank that website suggest is twice the volume of yours so please consider rehoming your last one or asking your uncle to take it back.
I also believe they need a smaller size substrate to protect their barbels. Sand is often used instead of gravel which can wear them away and/or cause infection if the gravel isn't maintained properly.

With regards to filtration, I would think that, unless you did something daft, like using bleach, the bacteria should have survived reasonably intact, however, when you add new fish, test the water daily until you have a complete week of 0ppm ammonia and nitrite. You only mentioned nitrite and nitrate previously, which suggests that you have paper strips. I strongly recommend investing in a liquid test kit, as these are far more accurate, and you can test for ammonia too. I have never understood why the strip test manufacturers don't include an ammonia test - it's the most commonloy needed one.
 
With regards to restocking, I would add my voice to those asking you to ask your uncle to take the Cory back. They are a shoaling species, and need to be in a group of 6 - and 6 of a fish that size is too much for a 35l tank.
 
Here's a few suggestions for what would be suitable.
 
A male betta with either 6 celestial pearl danios or 6 chilli rasbora (aka mosquito rasbora)
A pair of peacock gudgeon (aka peacock goby) with either of the above 2 shoaling species
8-10 of either of the above 2 shoaling species
2 pairs of peacock gudgeon (without the shoaling species)
 
I wouldn't suggest guppies, as they need the minerals found in hardwater in order to thrive.

I didnt use bleach or anything and my uncle tested the water for me, he put it in test tubes and then added a bit of liquid to each one to see what colour it turned and he said that they were all fine Um I will speak to him about my cory I did do a lot of research before buying any of my fish and I never found anything saying that he wasnt suitable for my tank size but thanks for telling me anyway as to be honest I had no idea he would grow too big. Out of the two celestial pearl danios and chilli rasboras which are the calmer ones as I prefer to have relaxing fish instead of racing and bombing around sorts, oh and I just washed my filter in tap water and I always add some 'tap safe' into the water once I have cleaned the tank out and I think that helps to keep the pH 7 and the other levels fairly normal  thank you in advance.

I have been looking at my cat fish for a while and comparing him to some online pics of salt and pepper cories I think he might be one as I have had him for about 6 months and he seems very small and I only guessed he was a peppered cory as my uncle just referred to him as a cory. I have started a new thread asking if he is a peppered cory or a salt and pepper, what do you think he is???

It sounds like you didn't cycle the tank if you just put water in the tank and kept testing it. You have to add ammonia and follow THIS.
I would re-home your pepper cory and do that and then go with one of the stockings TLM has suggested. I saw your other thread and he looks like a peppered cory to me, sorry.

Both species are pretty sedentary, probably the rasboras are slightly calmer, but there isn't much to choose between them.

are there any other stocking suggestions you could give me as my local fish shop doesnt have any peacock gudgeons and he said they could order some in from somewhere but my local fish shop try to breed most there fish in store and you can see the fish breeding and the babies growing up so if they order them in you have no idea where they are coming from really. So i would perfer to have some fish that they breed there. They have platies, mollies, rosy barbs and toger barbs, blue rams, gouramia, kribensis fish, zebra danios, neon tetras, white mountain minnows and guppies any other suggestions will be taken into account aswell and I think they also have a few other fish but they are all that I can remember

A single male betta and some shrimp or snails as none of the fish listed are suitable for this size tank except the guppies but those may not be suited to your water.

oh ok how many guppies would you recommend?

Again, guppies don't thrive in softwater, so I wouldn't recommend them for you, but in theory you could get 4 or 5 in there. Make sure you only get males, though, as you will probably get a population explosion if you have a female.