When I first acclimated fish I would float the bag, cut off the top, clamp it, then slowly add tank water and then after an hour or so plunk in the fish - everyone lived and was happy. I recently got a co2 system - all of my fish in the system adjusted fine (I tuned it up to a green drop checker slowly). The other day, I added 6 Amano’s and was extremely distracted (and perhaps showered with bravado of my previous successes) and had poor tank quality (high tds) - shocked them, killed them almost instantly. Since then, I cleaned up the tank and stabilized everything - got my drip acclimatize + a tds meter. I acclimated the water to the same tds as the tank (and temp). I spotted all Amanos (4 in total) and only 3/4 neons last night. Note: I added the fish mid-Ish co2 cycle and they seemed ok with the transition. Today, I lost 2 neons and only spotted 2 Amanos. My question: do co2 users do something different when acclimating fish to their “established” tanks? My thought: it seems that the more I learn, the more I think people pick their hardscape, pick their plants, and pick their fish (after several years of mistakes) all to suit the right parameters etc. They set up the hardscape, plant densely, flood the tank, set up the co2 starting it slowly while monitoring algae growth and start with low lighting. Add ALL the fish they want (use pre-cycled media that can combat the off-gas of the substrate or wait for the mini-cycle to finish then add the fish - with the low co2 levels). Then just practice husbandry of the plants and tank - and feed the fish. Then make several minor mistakes and rinse and repeat and optimize? I suppose we have to make the big mistakes first ? Oh ya, and how do I prevent this from happening in the future? What is the conventional practice for acclimation of co2 injected tanks? Also, some of the plants I added have started melting (the leaves became transparent).