Once males have been in with the ladies they hate going back to the "male cage". If there are other males in there it will usually result in a fight ... this can kill your males.
In the small tubs I keep 1:3 or 1:4 ... it really depends on what they are being used for ... pinkie and fuzzie tubs usually have 1:4 as I pull the babies pretty quickly. If I want to grow out the pups then I keep them in a 1:3 tub.
In the larger tubs I keep 1:5. This seems to be a good number regardless of whether they are pinkie/fuzzie tubs ... or grow outs.
Once they are weaned they get seperated by sex into tubs ... I usually keep about 10 weaned in a tub and the numbers lower as they get bigger ... The main reason for 10 to a tub at weaned is chances are youll get at least one smart rat that will figure out how to get food and water and the others will mimic it. At around 60 grams they go 6 to a tub and around 90 grams they go 4 to a tub (if females) or 3 to a tub (if males).
One male can easily take care of up to 10 females ... One of mine takes care of 15 ... these are future breeders and he is around 600 grams ... I definetly want his genetics passed on.
While I really like the bigger tubs they are too deep for pups and weaned to get at food and water ... it took about 8 lost litters before I figured out that was the problem.
Bryan
PS today I found a 90 gallon tub ... its about 6 ft long 3 feet wide and 12 inches deep. Im thinking this may make a good grow out tub for males. I'll post pics if i decide to get it ... but its $50 per tub.