When competitors are around, male Atlantic mollies try to hide their top mate choice, reveals a new study published online on July 31st in Current Biology, a Cell Press journal.

Fishery biologist Sandy Sutherland looks through the lens of the microscope at tiny sections of fish earbones, known as otoliths, each showing annual bands of growth. She carefully counts the bands to determine the age of the fish, then moves on to the next sample.

Humans have regularly been introducing exotic species into natural environments in order to provide for their nutritional necessities or meet less indispensable purposes such as horticulture, fishing or hunting. However, the particular environments are not always adapted for hosting new arrivals.

Results are in from last year’s fifth annual Bonefish Population Census in the Florida Keys and the bonefish population has remained fairly steady from 2006, however, the number of volunteers participating in the annual event continues to grow.

Aggressive territorial male Mozambique tilapia fish (Oreochromis mossambicus) send chemical messages to rival males via their urine. They increase urination, have smellier urine and store more in their bladders than less aggressive males, according to research published in the open access journal BMC Biology.

In the longest running study on how fish populations in coral reef systems recover from heavy exploitation, researchers from the Wildlife Conservation Society (WCS) and others have found that the fish can recover, but they need lots of time – decades in some cases. The study appears in a recent edition of the journal Ecological Applications.