Its true things have become more complex but its not really that difficult to memorize the important things once you know what you need to know, the main thing is to understand;
a. How the nitrogen cycle/water quality works, at the least the basics of it anyway, all is explained in the link below

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/www.fishforums.net/content/New-to-t...-tank-syndrome/"]http
/www.fishforums.net/content/New-to-t...-tank-syndrome/[/URL]
b. Know your fish- so that you are certain you are providing the right care and habitat for them, especially in the long term etc.
c. Always handy to know how to identify certain common diseases and parasites, and what things to look out for in a healthy fish of the particular specimens you keep, so you know what to do when things go wrong

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d. Know how to maintain/clean your tank properly and how to go about it and how often etc.
And thats basically it. People have progressed an awful lot in this hobby over the last 35years, in the past, few people understand how the water quality in their tanks worked and in the past fishkeeping for a lot of people was successful fishkeeping was just random luck and quite a hit and miss matter- a lot of the time, people would just stick a load of cheap random fish in when the tank was set up and see which ones survived over the next few weeks, then the owner would continuously add more fish as they saw fit etc.
For a lot of people unfortunately this is still the case as pet shops still give just as bad a advice as ever at times and a lot of people still unknowingly go on that bad advice, but the main thing is that you know your stuff before you go into the pet shop so you know what you're doing when you buy stuff and don't need to ask questions on keeping the fish you're about to buy etc. Less people are buying tankbusting fish now days due to the more access to better research sources, and less people are losing fish while cycling their tanks etc.
With common livebearers like mollys, guppys, swordtails etc, they used to be a lot hardier in the past, people used to recommend them a lot a the ideal beginner fish as they could survive through almost anything, but unfortunately now days a lot of common livebearers are becomming increasingly weak (namely guppys, from too much inbreeding) although most are still pretty hardy, not just that but they are a lot more naturally fragile/sensitive varieties commonly available in pet shops, so people need to pay a lot more attention to the proper care of such fish if they are to survive and lead a good quality of life and health etc.
But yeah, in a way, i actually think its a probably a good thing that there's a lot to learn about fish keeping, because i think not only does it make the hobby more involving and interesting, but people can keep fish a lot more successfully now days on success that isn't purely luck based but rather success that has come about from thorough research and knowledge by what the owner is doing, and also know for sure that their fish are leading a good quality of life and are in good health etc

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