I didn't even plan on having fish when it all started.
In 1995 (I was 5 back then), an old friend of the family (may he rest in peace) gave me 4 guppies (of red, blue and I think even green variety males and a pink-tailed female), though the tank they came with was maybe a 5L, long tank but very thin. My mother gave me her crystal rock which looked awesome in there but... it was that one thing that killed my fish in the end, as my mother accidentally put the rock in a soapy area on the sink while she was washing the guppy tank.
Around 1997, I visited another friend of mine and she had a huge tank with all kinds of fish (giant betta, 4 bettas in pairs, swordtails, a platy, one or two black mollies, some kind of golden tetras with a black spot on the back, baby angelfish, neon tetras, zebra danios, guppies and black widow tetras - not sure if there were other fish in there, it's been a long time). She said she could not take care of them as they were dying one by one ever since she got them and the tank water was quite murky. It was around 40L-ish or 50L.
She gave the whole tank to me, along with all the fish.
I somehow managed to clean it up but had no idea what a filter was or partial water changes. I used to change 100% water (and the fish had to sit in bowls during that time) once a week.
My dad kept getting fancy fish such as goldfish of all shapes and colors, Hoplos and a fossilis but only the Hoplos survived for a long time (I still have one from back in 2003). That aquarium had seen periods of having a filter but for a very short time, also had substrate of white gravel, then beach sand and with Elodea and lotus plants, but that didn't work so I had to give up on them due to not knowing how to stop the fish from eating the plants and how to clean the substrate properly.
The more sensitive fish died during summers or when my dad was in charge of the aquarium (my fault for having no filter/not convincing mom to keep one back then though but I had no idea how it was supposed to work), others died in accidents during water changes (such as slipping away or temperature shock due to too warm water), or me being a stupid kid and getting my revenge on some fossilis my dad bought which kept stinging me (the pain was pretty strange too, I just read recently that those fish are poisonous a bit) when I had to change the water (I fed it to the cat) or not having a lid the whole time and a Hoplo named Rex going overboard (ironically that one survived whole nights hiding through the house whenever he escaped and only one time he made the mistake to land in front of the balcony door and froze to death on Christmas eve...)
In late 2010, after my 8 year old Hoplo Seadra died, my mother confined my last 9 year old Hoplo Tzuppy to a 23L she bought for him since I had no other fish left.
In 2012 in January I bought 3 swordtails (1 female black berlin died during the first week due to my current female swordtail Bee attacking her. Though I had separated that one, she refused to eat till the end). Now I'm left with a pair (Bee the red female with red eyes and Cracker the black berlin male) and Tzuppy in the 23L.
I have introduced the filter on January 18th 2012 and my 3 fish survived so far with daily water changing (though at one point back in feb, my mom told me to do less frequent and for a week I did changes only once every 2 days in 90% proportion but then I managed to sneak the water changes daily). The problem would be not using dechlorinator so far so I'll find out if at least ammo is being processed today.
So it's time to change all that in 2012 and improve on fish keeping. I bought a 76L 85cm long tank with 30 width and 30 height and am preparing it for the fish.
Today I'm getting the ammo test and some dechlorinator (would be first time I'd use any of these) so I want to start properly but due to spending all my money on the new tank, fish food and that dechlor I'll get today and plants that I will get some other day, I'll need my dad's help for the rest of the cheaper stuff (sand, ammo test and later on nitrite test) and building a lid.
Then on my next salary I can look for a proper heater, as the one I've used for my turtle's pond just seems too damaged and I'm scared to use it.
EDIT: My dad already bought 2 kilos of white fine sand to sample it. Got 1 ammo test and dechlorinator Tetra Aquasafe. Hope the dechlo will work.