# Old Neon Tetras died after adding new ones



## Killitwithlove (Jun 16, 2019)

Hey everyone, 

I’m new to the aquarium world. I have a 10 gallon tank with a hang on back filter. We don’t use a heater because the water stays a constant 77-78 degrees Fahrenheit on its own (although the guy at the store said we’d probably need one for winter). It cycled for a week with no fish, but we added beneficial bacteria, Tetra Aqua Safe, and a little bit of fish food (what the guy at our local mom and pop aquarium store said to do). After a week we added 3 neon tetra, 2 mystery snails, and a black racer Nerite snail. They’ve all been fine since then (about 2.5 weeks). 

Anyway, we bought 4 more neons from PetSmart yesterday (we were told the tank was large enough for everyone). We acclimated the fish by turning off the light, putting the bag in the tank for an hour, then taking out their water and adding tank water every 20 minutes for another hour. We added the fish and I sat and watched them for a while.

The new guys blended in with the old tetras right away and everyone seemed fine except one of the new guys. I noticed then that he was missing his back fin and the “red” on his tail was more of a dull orange. I couldn’t find much about it online and left him in the tank with the others. None of them were picking on anyone and everything seemed fine. 

Well, I woke up this morning and 5 of the 7 tetras were dead (I assume all the new ones plus one of the old ones). I took them out of the tank and watched the remaining 2, they seemed fine. A few hours later we lost another one. Now we have 1 neon left and I’m worried he’s going to pass too. 

I can’t understand why my old ones are dying off too... 

Any thoughts? 

(By the way, we use API masterkit for water testing. All levels are 0 and PH is 7.3. We also do weekly 25% water changes)


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