2 Questions

[SirCastic]

So im' going to upgrade to a bigger tank (90 maybe 100), i was wondering if i took the old filtration from my 55 and all the water from it + gravel i could really jump start the cycle and maybe skip over it? treating like a 50% water change of course. Then i would add the rest as dechlorinated water. will this work? or will i still need to cycle?

Also i was thinking of getting a Black ghost knife when i upgraded, currently in my 55 i had 5 giant danios, 3 glass catfish, 5 tiger barbs, 6 mollies ( 3 black 2 dalmation 1 gold dust) 2 red wag platies, red tailed shark, blue crayfish, ghost shrimp, fiddler crab, chinese algae eater, 5 kuhli's and 1 stick catfish. WIll the BGK be aggressive? will it be enough room for him if it isn't? If not could i go with a dinosaur birchir eel instead? or just drop the eels altogether and get some more communities?

Any help is appreciated!

 

[slimeneo]

You only new to move the filter media, the gravel and water won't really make a difference. But as long as your mature filter media is in the new tank, it should be pretty much cycled but I wouldn't put too many fish in at once.

 

[JohnDyer]

All you need to move is the filter media, move the gravel too if you're still using it. But the filter media is only handling the bioload of 55 gallons worth of fish, so even in a bigger filter you'll need to add more fish slowly and monitor ammonia.
I would increase the number of Giant Danios and Tiger Barbs, they like their shoals to be as big as possible. Khuli Loaches also benefit from bigger groups. I've heard that Crayfish will catch and eat slow moving, injured, or sick fish. While Black Ghost Knifes get fairly large, they'll be sharing floor space with this guy.
I don't know much about the BGK, but the dinosaur birchir will grow large and eat other fish.