The mineral-fish fed off of ore veins in deep undersea caves. After taking the nutrients it needed for energy, it used leftover metals to create a thick exoskeleton with an armored carapace and a snapping beak. The mineral-rich shells were harder than plasteel and resistant to energy weapons, and were highly valuable as a result: a single meter-long organism could be worth 10,000 credits. The mineral-fish industry was a major component of the Andoan economy.
Andoan mineral-fisb were normally about half a meter long and were covered by a thick shell. They had a sharp spiked tail which was used to break up large rocks, but could also be deadly when used to defend against predators. They also had a number of shelled fins used for propulsion and to break rocks down into edible chunks; while seldom used in combat, the fins were rough and abrasive and could cause serious injury to anyone who brushed them. Because of their fins and incredible strength, Aqualish harvesting mineral-fish waited several hours for the fish to "suffocate" in the air before daring to extract the minerals from the fish.
The fish had a lifespan of three to five years, reaching full maturity after about one and a half years. Adult females could lay eggs about once every five months, producing hundreds of small, hard- shelled eggs which appeared similar to ball bearings. Females built nests in calm, shallow pools near the coasts, as fewer natural predators prowled those waters.
Andoan mineral-fish were once plentiful in the rich seas of their world, but they became a prime commodity in the wars between the two Aqualish races and their populations dwindled. Only after the Galactic Republic became guardian of Ando did the population return to pre-war levels. After the collapse of the Republic, the Galactic Empire once again began harvesting the animals. The Aqualish used mineral-fish as a cheap means of harvesting metals vital to their war efforts. As the Empire and the Rebellion competed for resources, the rare alloys they produced were critically important to the war effort. One of the alloys found in their shells was purified sedrellium, an expensive high-strength alloy used to reinforce the hull of the Incom Corporation's X-wing fighter. Great fishing platforms prowled the seas of Ando looking for mineral-fish schools to harvest. The shallow waters containing mineral-fish nests were patrolled by Imperial skiffs to prevent Aqualish from harvesting immature mineral-fish, but the Empire allowed unlimited harvesting of mature mineral-fish.
Experiments with controlled breeding of Andoan mineral-fish were a complete failure: Andoan mineral-fish placed in controlled environments did not survive more than two to three standard months and there were no recorded cases of eggs hatching while in captivity. There was also extensive research into their bio-chemical processing ability, but scientists were not been able to artificially duplicate it. A number of mining firms invested in this research in the hopes that a cost-effective artificial filtering process could be discovered.