Hi James,
Welcome to the forum! I think a lot of people are not online much at the moment because of the holidays as normally you would have had a few more responses
Its great to see that you are taking a real interesting in getting things right and you will get a lot of respect from people here for having that kind of attitude.
Going from what you have:
- 4.5g(uk) tank
This is a relatively small tank which does really limit your stocking options. It will also require a lot more work to keep running well and has a higher chance of something going wrong. For example if there was an ammonia spike in this tank it could wipe out all of the fish while in a larger tank with more water it would have been diluted and not caused such a problem (if any).
That being said however it is possible to keep fish healthy and happy in a small tank. You just need to do your research first (as you are doing
), pikc the right fish and keep up with the water changes and maintaince. There is somethign very rewarding about being able to sit back and watch your fish
I will go on to the possible stocking options later.
- 2 Artificial Plants
- 1.5Kg Decorative Gravel
Your call on these ones. If you like them then keep them. Depending on what fish you have you may, or may not, want to keep the plants. If you go for something like a betta you probably wont want any fake plants in there that have sharp edges so they dont catch their fins on anything. Personally I would recommend getting some nice silk type fake plants which look a lot more realistic.
A lot of fish do like to have areas to hide/explore.
- 12g Goldfish Flake Food
I honestly dont know what the difference is between tropical and cold water fish food. I would just bin this though and get some tropical stuff.
- Elite Stingray 5 Underwater Filter
Yep this is fine for tropical.
- 30ml Aqua Plus Water Conditioner
You will need dechlorinator eventually. You add this to the tap water when you do water changes to remove the chlorine and other stuff which could damage the biological filtration.
- 30ml Cycle Biological Supplement
As you said most people think these kind of things are complete rubbish. I would tend to agree. Not sure if this stuff is meant for cold water and tropical temps if it is supposed to be used for both then you might as well use it.
Things you need:
Heater: Yeah try and get a 25w heater. I doubt very much it would melt the plastic. They get hot but the water around them takes away most of the heat so not really an issue. If it helps to put your mind at rest I have had 150w and 200w heaters in buckets of water before and they got nowhere near hot enough to do any damage to the plastic.
Test kits: You need test kits for Ammonia, Nitrite and optionally also nitrate (notie the difference between nitrIte and nitrAte). It sounds like you have already read about this but the fish waste is basically Ammonia which is very harmful to fish, bacteria will grow on your filter which eat the ammonia and produce Nitrite which is also very harmful to fish. You will then get more bacteria growing in your filter which eat the Nitrite and produce nitrate. Nitrate is not harmful to (most) fish unless it is in very, very high quantities.
So you need to be able to test the ammonia and nitrite levels in your tank. Nitrate is useful to know but to be honest there is not a lot you can do about it for a 4g tank so just make sure you do weekly water changes to keep the levels low. Same goes for PH. It is good to know the PH of you water but as this is your first tank you really dont want to get into messing about altering the PH. If you get your water from a tap (and not from a well or other source) chances are it will be ok for the types of fish you are going to be able to keep.
Dechlorinator: As above. Add this when you do water changes.
Ammonia source: You wil need a source of ammonia to start the cycling process in your tank. i have used both fish food, frozen prawns and pure ammonia in the past. All of them work but the pure ammonia smells less and is the best option imo. Expect it to take at least 2-3 weeks to cycle. These 2-3 weeks are what annoy most new fish keeper as you obviously want to get some fish in your tank. Just think though that you wouldnt want to keep a dog in a box full of ammonia so you shouldnt want to do the same to fish which will also be your pets 9doesnt sound liek you are the type of person to do this though).
Decorations: Personally I prefer plants/wood/rocks to castles and bubbling treasure chests in my tanks but it really is your choice. Just make sure you have areas for the fish to swim in the open and areas where they can hide away. I would recommend wood with javafern attached to it. Looks nice and the plants also help take ammonia, nitrite and nitrate out of the water. Floating plants like salvina are also very good for this (and if you get a betta they love these for building bubble nests in). Just make sure you regularly remove a lot of it as it tends to grow quick and you dont want it covering the whole surface of the water (especially for bettas).
Fish:
4.5g is not a very big tank so you are limited. This doesnt mean that you cant get some really nice fish though. I would avoid guppies and other live bearers (molly's, platy's, etc) unless you only get all male or all female. its nice to breed fish but you need to find somewhere for the fry to live and a 4.5g tank will get over crowded quick.
Betta:
Personally I would agree with Snooks and go for a betta. Just get one male and it would have a lot more personality then any small fish you can keep in there. You could probably get a betta and around 3 pygmy cory's. If you go for a betta look for a local breeder as most lfs dont tend to have a very good selection and you can get some really stunning looking betta's ( I personally love the crowntail bettas).
Tetras:
You could go for 6-8 ember tetra's. These are some of the smallest tetras and would do well in this tank. Again maybe 3 pygmy corys as well for the bottom.
Glowlight and flame tetras could be another possibility as they are not as active as some of the other tetras so dont need quite as much swim room. You could also add some cherry shrimp in here as well (and maybe also to a betta tank though the betta "might" eat them).
There are other fish choices but these would be my "personal" recommendations as hardy, but nice, fish for a smalelr tank. You dont want anything that needs a lot of swim room, needs very large groups or gets to big.