Renowned energy trader Mark Fisher on Wednesday said the "worst is over" for the crude oil market following a six-week rout that has seen U.S. crude lose over a quarter of its value.

The MBF Clearing founder and CEO said he'd be a buyer right now rather than a seller.

The market outlook for crude oil has recently flipped. Investors were worried about a shortage of oil as U.S. sanctions shrank Iran's crude exports. But the market now expects supply to outstrip demand as the outlook for consumption growth weakens and Washington allows some Iranian crude shipments to continue.

However, Fisher theorized that much of the drop in oil prices is due to macro funds getting out of the crude trade and rotating into natural gas futures. He argued that for years, buying oil and selling natural gas has been a huge winner.

"In no short period of time this trade has imploded," he said. "And I'm sure there is a ton of people getting, you know, margin called out of this trade, where they're being forced to buy nat gas and sell crude oil, and that's added to this ... new debacle."