A compact high-brightness LED aquarium light fixture is described for use in illuminating aquarium tanks artificial light. The LED aquarium light uses a densely-packed array of high-brightness light emitting diodes (LEDs) that are not individually packaged, where the array behaves similarly to a point source of light. The LED chips are distributed laterally over an area, where the LED chips have light emitting surfaces for emitting light in directions transverse to said area, wherein the dimensions of the area do not exceed 25 mm. Adjacent chips of the array are preferably separated by less than about 0.2 mm. The extended point source LED array, with its lens and associated reflector, result in a concentrated light source that attractively illuminates the contents of the aquarium, and creates a desirable shimmering effect within the aquarium. The compact LED aquarium light does not block much of the top surface area of the aquarium, thereby allowing unimpeded access to the top of the aquarium for viewing the aquarium, and also for tasks such as feeding, tank cleaning, and other aquarium maintenance. The LED array contains a plurality of LED strings that may be separately controlled, thereby allowing the spectral content of the LED aquarium light to be varied, to facilitate desired aquarium viewing conditions, as well as promoting the growth, health, and other desired attributes of various forms of marine life such as marine plants, algae, and coral. Multiple wavelengths of LEDs may be used within each LED string, thereby allowing the ability to further optimize the spectral content of the LED aquarium light. Due to the compact size of the LED aquarium light, the light emitted at each of the multiple different wavelengths from the array is evenly distributed, when the objects being illuminated by the array are at a distance of less than about 3 feet or even less than 1 foot from the array. A clamp-on, flexible gooseneck mounting arrangement allows for the use of one or more compact LED aquarium lights with aquarium tanks of various sizes and dimensions.