I recently added some ghost shrimp (around a dozen) to a 15 gallon with a betta. I used the drip acclimation method for almost 2 hours. I added them to my tank with no die-off for around a week and put in cuttlebone. There were a lot of molts. Then I had a plant start dying and shedding a lot of leaves overnight and had an ammonia spike which killed around 3 shrimp so I did a 50% water change and made sure the temperature was the same. Since last week 1 or 2 shrimp have been dying every day. Today the last one died. 0 ammonia, 0 nitrite, and 5-10 nitrate. My tiger nerite snail is fine. What could be the reason for their deaths? Maybe they came with a disease?