The 27-year-old played six matches for the Nuggets, averaging 23.5 points and 10.3 rebounds.
But the product of South Carolina University injured his right foot two weeks ago and was yesterday released by the franchise.
Nuggets coach Alf Arlidge said the franchise made the decision after receiving medical advice suggesting Tisby's injury would take longer to heal than the team could wait.
"We just really need someone who is 100%," Arlidge said.
"The guy has been out for two weeks now ... and he is still quite ginger on it.
"I need someone who can run up and down, not someone who can hobble up and down [the court]."
Earlier yesterday, Tisby told the Otago Daily Times he had been doing some light training and rated himself a 90% chance of being fit in time for the game against the Southland Sharks in Invercargill on Saturday.
"I've been putting a little more weight on it than I was last week, and moving around a little better," Tisby said.
"It is nothing serious. I didn't fracture anything.
"It is just a joint in my foot that is inflamed which is causing me some pain."
Tisby, who played 11 games for the Nuggets in 2008 and led the league in rebounds that year, was shocked he had been released.
"I don't really know what to say. I felt like I was ready to go.
"I was trying to get myself back together and get everything all right.
"It is just a tough break."
Despite missing the last two rounds, Tisby, who leaves Dunedin on Friday, is in the top five in the league for scoring and rebounding and is holding on to fourth place in the player power rankings.
In his absence, the team has struggled on the boards, particularly against the Nelson Giants, who out-rebounded the Nuggets 52-28 at the Edgar Centre two weeks ago.
"I think it would be a waste of time to have hard feelings.
"At the end of the day it is a business.
"I don't agree with the decision that has been made but there is not much I can do about it."
Arlidge said the franchise would look to replace Tisby as soon as possible.
"We are looking at about three guys. We are hoping that will be finalised by Friday.
"We might miss the boat this weekend but that is just the way it is."
Meanwhile, fellow United States import Tyler Amaya is struggling with tonsilitis.
While he is expected to play, it is another setback for the Nuggets, who are eight games into their comeback season and yet to win.
He got out of the sick bed last week to help the Nuggets put up a strong showing against the Sharks.
With Tisby sidelined, Amaya carried a heavy burden and will once again have to shoulder the lion's share of the scoring responsibilities.
"We are getting there.
"Every week we are making steps and the guys are starting to believe in themselves.
"That's what I set out to do at the start of the year," Arlidge said.
