I used to run a 75 gallon tropical freshwater, and recently downsized from a 55 gallon to one bully betta fish who is now the queen of her very own, planted 5 gal long.
I agree to the above advice regarding Platy’s needs for filters, heaters, and needing a school of 3+ fish. More is better, but you would need a larger tank.
A twenty gallon long is the smallest I would recommend; you can get away with a ten gallon, and plan on upgrading size when you get the chance; i find a lot of cheap aquariums on facebook marketplace and garage sales.
Platy’s are very active, fast swimming fish with quite a bit of power when they want to go zooming about, so a long tank is better than a tall tank.
You want more than 2 fish because as a schooling fish, they feel safest with lots of friends around them (and a safe feeling fish means a healthier fish, as stressed fish sucumb to disease and parasites far more easily), and the numbers will also mean no one fish gets bullied to death and picked on if their schoolmates prove to have any aggression.
I use I think it’s TOPFIN Spectrum (blue lid, circular fat bottle with a shiney label) food? They use garlic in the ingredient list and it’s been my go-to for community fish food.
I prefer pellets to flake food as they seem to get eaten more consistently, completely, and dirty the water less.
Look up “how to cycle an aquarium” and read up on the nitrogen cycle. This will equip you with knowledge to understand why and when your aquarium water needs to be changed, and how to maintain it.
I would not use the bottled mineral water for your aquarium, UNLESS your tap water is unsafe to drink or something. Just use a water conditioner; your water parameters can change a little bit. It’s dramatic, sudden shifts that hurt fish.
I have been using Prime water conditioner for years. We have well water heavy in iron, so this one neutralizes the heavy metals in our water to be safer for the fishies. One bottle last forever because it’s literally two drops per gallon of water, and it’s good quality stuff worth the price. My second choice is Api Stresscoat; some people are wary of it due to the aloe vera content, as it can coat the gills and make breathing difficult for fish. On the flipside, it can also help their slime coat and promote healing, so i use it when i add new fish or when i have fish in hospital tanks, and make sure i have an air bubbler.
Fish can, in fact, suffocate. You want an airstone in your tank. Filters can fail, don’t count on them to supply oxygen to the water.
I once came home to, after months of fighting a columnaris infection in my 75 gallon and having moved the remaining fish into a new-new quarantine tank, a tank full of my clown loaches gasping their last breaths just in time for me to see them die, because the filter in the tank failed while I was at school and I had neglected to install the airstone/pump before leaving.
aquarium forums are an absolute wealth of information. The basic things you would greatly benefit to know more on:
-the nitrogen cycle, and how to cycle an aquarium
-water parameters, and how to accurately measure them (i use an API liquid test kit, though in honesty, once my aquarium is cycled i rarely use it unless i think something is wrong. Liquid tests are more accurate than dip strip tests, provided you do them correctly.)
-Platy’s natural habitat (understanding how they live in the wild will help you make changes in their aquarium to make them more comfortable)
-tankmates, if you want them.
I usually keep a small bristlenosed plecostomus (20 gallons minimum, and they do better in a 40 gal long+) for cleaning up algae, and snails, for my “cleanup crew”
They’ll eat fish food the free swimming fishes miss or leave as crumbs. You do also need to feed them their own algae tablets, so they do not starve or lack vital nutrients in their diet.
-fish diet
Some aquarists can and choose to go full out and feed their fish live foods and fresh veggies. I give veggies as a treat or for medical care sometimes, but i’ve otherwise just used pelleted food. The easiest meal plan is to know what nutrient balance your fish species needs, and just get a food that fits it.
For example, i have a betta, and they are primarily carnivores who need a high protein content. There are foods on the market labeled for bettas, that don’t actually meat their nutritional needs! (Bah duh tsh)
Sorry i kinda rambled all over the place, but i hope any of that is helpful.
If all the fish could hide from sight of both people and each other at the same time without crowding together, the tank is probably big enough.
