u/RecentInteraction302

I’ve had this 30g aquarium for a few months, with almost every decor substrate and fish coming from a year old 20g. It was perfect until a couple weeks ago. I got some new fish, 6 kubotai rasbora, 3 more kuhli loaches, and 5 orange cherry shrimp. Since then, it’s been a tank massacre. So far I’ve lost 5 of the kubotai rasbora, 7 ember tetras, 4 kuhli loaches and 3 marble hatchets. I got them from aquarium adventure in Columbus (I usually don’t shop there but I had store credit) and thoroughly inspected them during acclimation. None of the store water went into the tank and everything seemed in good health. I’ve been doing daily testing with an api master test kit and the results are consistent: 0 ammonia, 0 nitrite, 5-10 nitrate (plants have always consumed most of it), 7.2-7.6ph. I’ve upped water changes from weekly to 50% twice a week. Does anyone have ideas on what could’ve caused this? I feel terrible not knowing the problem or solution.
Edit: I wanted to retire this tank after everything died out from age, but I cannot in good conscience have the remainder of the fish live stressful lives. I want to restock but I don’t want to until I can solve whatever problem I have. The tanks down to 4 marble hatchets, 1 kubotai rasbora, 2 ember tetras, 2 kuhli loach, 2 juvenile bn plecos, 3 otocinclus, and however many snails and shrimp I have

My girlfriends coworker asked if I wanted some fish, said he was just going to kill them if I said no. So I wound up with 2 3 spot gourami, both males, and put them in my 75g African tank. I haven’t been able to get them to come out, they’re very skittish, but what’s more concerning is I have not seen them eat. It’s been about 5 days since I got them and I do not believe they’ve eaten anything within that time.