Kona-based Cyanotech Corp. more than doubled its earnings in the latest fiscal year, largely due to strong demand for its micro-algae nutritional supplements, the company reported Thursday.

Cyanotech’s net income rose to $3.6 million, or 66 cents a share, for the 12-month period ending March 31, up 110 percent from $1.7 million, or 32 cents a share, during the same period a year earlier. For the final three months of the fiscal year, net income totaled $1.2 million, or 20 cents a share, up 46 percent from $795,000, or 14 cents a share, in the year-earlier period.

Cyanotech makes high-value nutrition and health products from micro-algae at its 90-acre facility in Kona. Sales of its branded Spirulina Pacifica and BioAstin Natural Astaxanthin products rose to $24.6 million in fiscal 2012, a 46 percent increase from the previous fiscal year.

Cyanotech distributes the products in bulk to nutritional supplement, nutraceutical and cosmeceutical manufacturers and marketers in the United States and more than 50 other countries.

In a separate quarterly regulatory filing, Cyanotech officials said competition in the spirulina market remains high due to a large number of suppliers. They said Cyanotech is responding by emphasizing the "higher quality" of its product.

Competition in astaxanthin sales, by comparison, is less intense because of the limited number of suppliers and increasing demand.

"Because of this, we expect current producers to increase capacity to meet this increasing demand, placing further competitive pressures on us in the future," according to the filing.

Cyanotech’s shares closed up 1 cent at $7.21 Thursday on the Nasdaq Capital Market.