This species has been recorded from the Guaporé, Madeira, Branco, Trombetas, and Urubu river systems within the Amazon river basin, Brazil.

Type locality is ‘Igarapé Jatuarana, 5 kilometers above Samuel, Rio Guaporé, Rondonia, Brazil’.

Widely-distributed throughout the Amazon, Orinoco, Essequibo, and Tocantins river systems in Brazil, Peru, Bolivia, Ecuador, Colombia, Venezuela, and Guyana.

Type locality is ‘Rio Cupai [= Rio Cupari], Rio Tapajós basin, Amazon River drainage, Pará State, Brazil’.

This species is known from the rio Negro within the Brazilan Amazon basin and upper Río Orinoco system in Venezuela.

Type locality is ‘Rio Adujá, Rio Itú, tributary of middle Rio Negro, Amazonia, Brazil’.

I. geisleri is typically exported for the aquarium trade alongside the similar-looking congener I. adujai (Géry, 1970) but can be identified by presence (vs. absence in I. adujai) of a black lateral stripe on the body beneath the red stripe, and possession of 20-25 (vs. 28-34) anal-fin rays.