Water changes with new fish.

[Howlett24]

I agree that loaches or cories, but not both. Given the secretive nature of the kuhlii (they are ofteen nocturnal) the cories might provide more interest. You need a sand substrate (for either for that matter).

GH of 75 I will assume is 75 ppm (rather than 75 dGH which would be practically solid rock!) so this is soft to very soft. Forget livebearers (platies, guppies, and also mollies, swordtails, Endlers) as these need dissolved mineral in the water and thus a much higher GH. They willnot be healthy or last long in soft water.

Numbers look OK, nitrate at 20ppm is high but presumably this tank recently cycled so that should come way down. You could do water changes to get it down faster.

Is the water hardness easy to manipulate? And for what it’s worth I have a decent amount of live plants in there as well.

 

[Salty&Onion]

I wouldn't actually do anything with your water hardness. I would only choose live stock compatible with your water.

 

[Byron]

Is the water hardness easy to manipulate? And for what it’s worth I have a decent amount of live plants in there as well.

I agree with Salty&Onion. It is possible to adjust parameters but it is not a simple issue and one must understand the ramifications. It is always easier and safer to select fish suited to your source water. It makes water changes much easier...and every aquarium should have a weekly change of 50-70% regardless. Having to prepare this water with different parameters outside the aquarium means having some type of containers large enough to do this in advance. And any emergency water changes can be difficult if you cannot just use the tap water.

Thee are so many suitable fish, you are lucky. Many people have hard water and can't find suitable fish or a limited selection. From the perspective of parameters, almost any fish from South America and SE Asia will work.

Live plants are excellent. They do soften water but very minimally, not enough to make any difference.