Cycling an old tank???

[Julianasbetta]

So I have a 5 year old tank that has been in use for 5 years, but after moving to a different house, my family and I kinda left the tank on a table and let it sit with old water filled with poop, old fish food, and possibly some old fish corpses (s.i.p), and it has been that way for about a year... Is it necessary to do cycle the tank for a whole month or so on the tank if I want the water to be safe for my fish?? (It’s a ten gallon and I’m planning to add a male betta and MAYBE neon tetras or white cloud minnows) Thank you!!

 

[Colin_T]

flush it out and start again.

you don't know what chemicals from dust has settled in the water and if it had dead fish in the water is going to be bad.

take everything out and wash it down and start again.