The mitochondrial DNA coupled with A. iberus's geographic distribution has been able to affect their population genetic structure gradually in different spaces.

The males are marked with bluish to silver-colored vertical stripes on the flanks and dark bands on the caudal fin.

The females are generally greenish-brown with dark blotches distributed irregularly over their bodies; their fins are transparent and mostly unpatterned.

From an evolutionary ecology point of view, this lifestyle is highly adaptive for fish that live in unstable environments, such as estuaries, where unpredictable conditions increase mortality.

This strategy allows the toothcarp to exploit environmentally favorable conditions during the short intervals in which they occur, thereby revitalizing the population.

[7][8] Spanish toothcarp inhabit shallow, slow-moving bodies of water such as river-mouths, coastal lakes, and ponds.

The Spanish toothcarp is characteristic of the Iberian Peninsula, and extends from the Aigüamolls of Alt Empordà to Lake Adra in Almería.

In the last two decades, the Spanish toothcarp has suffered a severe decline,[11] due in part to destruction of suitable habitats.

The results for nuclear genes were consistent with those for mitochondria, and demonstrated that the Atlantic and Mediterranean toothcarp populations derive from separate lineages.

This discovery makes it necessary to separate the Atlantic and Mediterranean populations in order to protect their diversity and genetic identities.