Ok so i had my baby oscar in a 30gl tank for a about 4 months and he is about 6 inches long. I just bought a 80gl bowfront and i was wondering if i fill the 80gl tank a little more then half way, then use the 30gl water to fill the rest would i need to cycle it? I already have the filters cycled, and im moving all the decorations in there also. Or Should i just cycle the whole tank? Thank you.

When you say you already have the filters cycled, are you talking about the filters on the new tank? However, if they are completely new filters on the new tank then you will have to cycle it, simply adding water from an existing tank will not be enough, it will add a little bit of bacteria, but it won't really make a lot of difference.

If the new tank is not cycle that I would advise against moving your oscar straight into it. What you could do is use some media from your existing cycle tank and seed the new filters. Get yourself a load of small community fish and get the tank cycled. Your fish is better off workers for the moment, although the tank is far too small for an adult Oscar.

I have had the new filters in my old tank for about 2 weeks while i was on vacation.
I will just cycle the new tank just to be safe, I was just trying to move this fish because its in my bedroom and i need more room because i have a baby coming in 2 months. Just trying to get it done, but i dont mind waiting.

JSoscar89 wrote:

if you do not have any issue of locating the tank, yes, you can fill the bigger tank
halfway, move the existing filter and the new partially cycled filter in the new tank
and transfer everything, water and fishes.... you will have an established cycled
tank right away...

When we talk about cycling a tank we actually mean cycling the filter. A cycled filter is one where lots of bacteria live, these bacterial turn fish waste (ammonia) into nitrite and then into nitrate. These bacterai naturally come to live in the filter but it takes them several weeks to multiply to the stage where they can turn all the ammonia into nitrate. See the section on the homepage about cycling

So yes move your old tank water into the new tank but most importantly move your old filter onto the new tank. If you have new filters then leave the old filters on the new tank for 6 weeks and then remove them

ok what you guys said I already done. I wanted to make sure what i was doing was correct. He/She loves their new home.