oscar

[Fish on Fire]

You don't need to move the old water over but the substrate, any decor, and filter, yes.

Fill the 75, treat it with prime, let it sit for a little with the heater getting it up to temp, move the substrate and filter over, then add the oscar and you should be fine.

 

[Jc_Aquatics]

If it were me I would move ALL the water and media from the 20G to the 75 and add some more to the 75, move the filter you have on the 20 to the 75 (even without the filter you are waiting for). You can add a sponge filter during the time you are waiting. You'll be fine. I would do a water change a couple days after you add the old water. I use used water and old filters to quick cycle tanks all the time with no issues.

I was wondering if oscars can go bare bottom. Do they need gravel? Sometimes I see min poking around in it.

 

[Jc_Aquatics]

I was wondering if oscars can go bare bottom. Do they need gravel? Sometimes I see min poking around in it.

Also i was thinking of filling the tank today heating it and adding the fish tomorrow

 

[tlindsey]

I was wondering if oscars can go bare bottom. Do they need gravel? Sometimes I see min poking around in it.

You can do bare bottom its a preference. Personally I like some kind of substrate in my aquariums.

 

[tlindsey]

Also its typical for most cichlids to dig and move gravel lol.

 

[duanes]

Substrate (whether sand or gravel) provides much more surface area for beneficial bacteria to colonize than bare bottom. That, besides the normal natural security blanket and comfort that Tom has already mentioned.
And since a 75 is tiny, you need all the beneficial bacteria you can get.

 

[DawnMichele]

My Oscar Big Boy LOVES to move gravel around!!!

 

[Rmelz]

Substrate not only gives the fish something to play with but it is also good for beneficial bacteria to grow on.

 

[Rmelz]

You don't need to move the old water over but the substrate, any decor, and filter, yes.

Fill the 75, treat it with prime, let it sit for a little with the heater getting it up to temp, move the substrate and filter over, then add the oscar and you should be fine.

I would absolutely reuse the water. It's already cycled and will aid in cycling the new tank. I do it with my African fry all the time.

 

[Fish on Fire]

I would absolutely reuse the water. It's already cycled and will aid in cycling the new tank. I do it with my African fry all the time.

It's not the water that gets cycled. The water actually has little to no benefits when it comes to whether a tank is cycled or not, it's the objects within the tank that provide a surface for the bacteria to colonize/live on that is what gets "cycled".