Made a mistake!!

[Jazz.pliego]

I made a super big mistake!!
I have had my fish for about 2 years now and they have always been in a 26 gallon tank
Originally we got 8 fish. (5goldfish, 3 tetras)
But outof the eight only 2 gold fish and 1 tetra survived...
My goldfish grew super big so we decided to get them a bigger tank... we set up the tank (55galons) and i put my fish in there after only 5 hours of the tank actually running
And JUST NOW after 2 years i am reading about all these different things like CYCLES and BACTERIA
My bigger fish started to sit at the bottom of the tank and thats why i started searching for answers, im freaking out i dont know what to do to make this new tank safe for my 5 fish now ( we also added 2 new tetras so ours wouldn't be lonely)

PLEASE HELP!!! WHAT DO I DO

 

[guppylvr11]

Is your water hazy? Water parameters?

 

[UntimelyLord]

If you have filter media from the old tank and it is still wet, put that in your new filter. Same for gravel/substrate from old tank. This will help get the beneficial bacteria colony going a lot faster. I would do 50% water changes every day until the tank is cycled. You will need a test kit to know how your cycle is going. Make sure it tests ammonia, nitrite, and nitrate. The most accurate is the API Freshwater Master Test kit (this is a liquid test kit with test tubes). Seachem Prime is a great water conditioner that can also temporarily detoxify ammonia and nitrite so that they are not dangerous to fish but can still be converted by the beneficial bacteria. You can use this to triple dose for the whole volume of the tank every 24 hours.

 

[ColoradoMollies]

Also, temperature? Do you keep thermometers? I wonder if they are cold and/or also in shock from that change.

 

[Jazz.pliego]

I tested the water out with the water/drops test kit
And this is what i got

Ph= 7.6
Ammonia= .25 ppm
Nitrite= 0 ppm
Nitrate= 5.0 ppm

Water is mabey from 69-72 degrees F
I also added the old filter in so now i have two filters working on the tank

 

[Jazz.pliego]

I tested the water out with the water/drops test kit
And this is what i got

Ph= 7.6
Ammonia= .25 ppm
Nitrite= 0 ppm
Nitrate= 5.0 ppm

Water is mabey from 69-72 degrees F
I also added the old filter in so now i have two filters working on the tank

 

[UntimelyLord]

Good idea adding old filter. .25 ppm ammonia is dangerous so I would keep up on the daily water changes. The fact that you have nitrate is good because it means that you have some cycling bacteria still and are closer to being cycled.
The temperature range for tetras is 74-78 while for goldfish it is about 68-74. Ideally these fish will be in separate aquariums but if you can keep the temperature at 74 that would be the best for the situation. I don't know what type of tetra you have but you should know that if the tetras can fit in the goldfish's mouth and the goldfish can catch them, the goldfishes may eat the tetras.

 

[Jazz.pliego]

I have the white skirt tetras, and i have had them in the same tank for 2 years and they dont seem to bother them.. but it is good to know that its a possibility so i can keep on eye on them