You would have to eat three plums to get the same amount of fiber found in one serving of pistachios.
Nutrient Rich
Nutritional Benefits in a Nutshell

The health benefits of nuts have been demonstrated in many studies. In general, nuts have been shown to help support a healthy heart and to be a source of both protein and fiber, along with many other important vitamins, minerals and phytonutrients. But all nuts are not created equal.
Crack Open Nutritional Benefits of Pistachios
A 30g serving (about 1 ounce) of pistachios has 49 kernels, 170 calories and a variety of different vitamins, minerals and beneficial phytonutrients. This little nut comes out big on nutrition.
Excellent Source of Important Vitamins and Minerals
Pistachios are an excellent source of copper and manganese, and a good source of phosphorus. They’re also an excellent source of vitamin B6, offering 20% of the Daily Value per serving. In addition to vitamin B6, pistachios are a good source of thiamin (15% DV) and have lesser amounts of other B vitamins, such as folate and biotin at 4% DV, and riboflavin, niacin, and pantothenic acid at 2% DV.
A Good Source of Fiber
Most Americans take in much less than the recommended 14 grams of fiber per 1000 calories.1 As a good source of fiber, pistachios can help meet this goal. A serving of pistachio nuts provides 3 grams of dietary fiber, or about 12% of the Daily Value. This is twice the fiber in an ounce of walnuts, and about the same amount as in a serving of oatmeal.