My Danios Need Help

[aquariumnewbie]

I set up a 20 gall tank that was originally meant to be for 12 neon tetras, but when I went to the pet store and lady working there said it would be okay to mix them in with zebra danios which made sense to me since they were being kept in the same tank. I brought home four tetras and four danios planning to add more after four or five days. I acclimated the fish for around four hours and they seemed curious and alive in my semi planted tank. As the days went by. I noticed that the danios ate most of the food leaving barely any for the tetras and that they were generally more skittish. They mostly swam on their own unlike the tetras who stayed close together, and were a bit more nippy. Four days later, I found a dead danio, and one sinking upside down. The tetras seem completely fine, but the one who swims for a bit, flips over and sinks had been swimming diagonally near the surface for a day now. As the day went by I noticed he no longer swam for a bit then sank. He's alive but now he's just sitting on the bottom upside down not doing anything. He also has "cuts" and brown discoloration on him and i have no idea why, since no other fish has it. Can someone help??

 

[Aiken Drum]

- Is your tank cycled?
- Do you know your water parameters? pH? Ammonia? Nitrite? Nitrate?

 

[aquariumnewbie]

My tank is cycled and it is a little cloudy since I just fed them but I don't know the parameters because I forgot to buy the kits and I thought I would get it once I bought the other fish.

 

[Aiken Drum]

How did you cycle the tank? If you dont have testing kit how do you know it is cycled?

 

[aquariumnewbie]

I know it's cycled because I used the water from my old tank housing mostly amano shrimp and guppies to fill it up, which had been running for over a year.

 

[Aiken Drum]

Transfering water from one tank to another wont cycle the new tank.

 

[aquariumnewbie]

Yes it would. Using water from an already cycled tank and using an already established bio filter makes it so that there is already beneficial bacteria in the tank. If the biofilter and water are the same from a thriving tank, why would it negatively affect new fish especially if I had let the tank run with a few shrimp and fish a week prior to adding the tetras and danios?? I don't see how you asking me about *how* I cycled the tank is going to help my identify the disease only one of my fish has.

 

[Aiken Drum]

You moved filter media as well? You didnt mention that.

 

[aquariumnewbie]

I moved part of it yes. I had a double filtration system (penguin 300) because of the size of my old tank which I moved, along with the water, to my new tank. I still don't know how knowing that could help me with my sick fish, who is now dead, since like I said NONE of my other fish have EVER had this problem. One died of unknown causes, one is sick. None of my other fish have displayed any level of concerning behavior.

 

[Aiken Drum]

Because 99% of the time when people come on here asking for help with fish dying after being introduced into a new tank its because the tank isnt cycled. Of those 99% most if them dont even know what cycling is and think that running a tank for a few days is cycling because thats what the pet store told them. I was just trying to establish if you had cycled the tank.

 

[aquariumnewbie]

Well yes, my tank is cycled and no, cycling is not the problem. So why did two fish die when all of them are healthy? The first had already become so discolored that I wasn't able to identify any skin diseases, and the second had tattered fins, brown discoloration, "cuts" and what seems like a swim bladder malfunction. It died sunken upside down while the first died floating. I'm very confused.