Mineral-fish are shellfish that form hard outer shells composed of incredibly valuable metals and alloys. They have an extremely high metabolism and produce a great deal of heat. What makes them valuable is that they survive solely on minerals and metals. Their digestive system filters the various metals and ores - harvested mineral-fish contain rich deposits of valuable metals and ores within their shells and internal organs.

The Aqualish used mineral-fish as a cheap means of harvesting metals vital to their war efforts. As the Empire and the Rebellion compete for resources, the rare alloys they produce are critically important to the war effort. One of the alloys found in their shells is purified sedrellium, an expensive high-strength alloy used to reinforce the hull of the Alliance's X-wing fighter.

Mineral-fish are found in large schools near rich deposits of minerals; in fact, Aqualish undersea mining expeditions follow mineral-fish to determine where to establish new mines. Great fishing platforms prowl the seas of Ando looking for mineral-fish schools to harvest.

Andoan mineral-fish are normally about half a meter long and are covered by a thick shell. They have a sharp spiked tail which is used to break up large rocks, but can also be deadly when used to defend against predators. They also have a number of shelled fins used for propulsion and to break rocks down into edible chunks; while seldom used in combat, the fins are rough and abrasive and can cause serious injury to anyone who brushes them. Because of their fins and incredible strength, Aqualish harvesting mineral fish wait several hours for the fish to "suffocate" in the air before daring to extract the minerals from the fish.

They have a lifespan of three to five years, reaching full maturity after about one and a half years. Adult females can lay eggs about once every five months, producing hundreds of small, hardshelled eggs which appear similar to ball bearings. Females build nests in calm, shallow pools near the coasts, as fewer natural predators prowl those waters. These waters are patrolled by Imperial skiffs to prevent Aqualish from harvesting immature mineral-fish, but the Empire allows unlimited harvesting of mature mineral-fish.

Experiments with controlled breeding of Andoan mineral-fish have been a complete failure. Andoan mineral-fish placed in controlled environments do not survive more than two to three standard months and there are no recorded cases of eggs hatching while in captivity.

There has been extensive research into their bio-chemical processing ability, but scientists have not been able to artificially duplicate it. A number of mining firms have invested in this research in the hopes that a cost-effective artificial filtering process could be discovered.