Not gonna lie, the odds are good most of these fish will not make it very long through no fault of your own - carnival fish are not exactly well taken care of before being ended off to kids with sticky hands.
That's really fair. I've always hated the concept of carnival fish for this reason. I know they're basically abused which is part of the reason why I want to try my damndest to give these little guys a shot. I know inevitably some of them will die young, sadly.
Yes, that tank is way too small, but you're already aware of it
This may sound pretty jaded - I may be down to a few within a week just because of the state I received these fish in. But this is a cheap $20 tank, and my goal is to get as many living happily for the next month or two until my partner moves into the new house. I'll likely buy her kids a properly sized fish tank as a housewarming if I can nurture these guys back to being healthy and happy.
As far as cycling, get a master test kit to monitor ammonia, nitrates and nitrites and do regular partial water changes (with 8 fish in 10g, you will need to do partial changes really often during cycling and monitor very closely because that ammonia is probably going to climb up fast.
Would partial changes every 2-3 days be sufficient you think? Obviously it's very dependent on the state of the aquarium. Right now I'd call the water "a little bit milky." I'll grab a test kit off Amazon (it's half the price as in-store, right now) but won't get it until Wednesday. API recommends this if ammonia or nitrates are too high:
https://smile.amazon.com/dp/B006YG12F6
Would that be sufficient you think to at least get the aquarium stable for these cute dudes?
Thank you for the response!
I like to avoid the use of heaters if possible because they can fail and electrocute your turtle and potentially burn your house down.
Ask yourself how cold do you let your house get ever? Is it above 60f? You don't need one then.
I recommend this timer. I have 3 of them: GE 24-Hour Heavy Duty Indoor Plug-in Mechanical Timer, 2 Grounded Outlets, 30 Minute Intervals, Daily On/Off Cycle, for Lamps, Seasonal, Christmas Tree Lights and Holiday Decorations, 15075 https://www.amazon.com/dp/B00366JSNU/ref=cm_sw_r_cp_apa_i_eFQpFb4MJG3TJ
Don't feed your turtle daily or worse twice daily.
Change your UVB/UVA bulbs every 6 months if they are CFL like this one: Zoo Med ReptiSun 10.0 Mini Compact Fluorescent Lamp https://www.amazon.com/dp/B00A8RHTYU/ref=cm_sw_r_cp_apa_i_VGQpFb6P1DE4G
YBS need extra UVA/UVB so go with the bulb I linked or a similarly powered one.
You also need cuttlebones. Exo Terra Sepia Bones for Turtles https://www.amazon.com/dp/B002YPZDBK/ref=cm_sw_r_cp_apa_i_eIQpFb2ZFDZR0
Any cuttlebones will do though.
Here's my water treatment: API QUICK START Freshwater and... https://www.amazon.com/dp/B006YG12F6?ref=ppx_pop_mob_ap_share
API TURTLE SLUDGE DESTROYER... https://www.amazon.com/dp/B00ESBHN1Q?ref=ppx_pop_mob_ap_share
API TAP WATER CONDITIONER... https://www.amazon.com/dp/B004LO9KSY?ref=ppx_pop_mob_ap_share (FYI you almost certainly have chloramine not chlorine in your water.)
API AMMO-LOCK Freshwater and... https://www.amazon.com/dp/B000255N0A?ref=ppx_pop_mob_ap_share
Get this to test your water: API Freshwater Master Test Kit https://www.amazon.com/dp/B000255NCI?ref=ppx_pop_mob_ap_share Ammonia, nitrates, and nitrites are your enemy.
Don't buy a dock. Make one from egg crate diffuser materials and zip ties: https://youtu.be/KDb6cv5I9Tg
Your turtle needs to get fully dry on top and bottom or they will get shell rot. I had a zoomed dock that cost 50$ and I replaced it after a scare with shell rot.