Despite ongoing threats, this species occupies a moderately large distribution. As such it is tentatively assessed as Least Concern. However, given local extinctions and significant impacts of mining activities and invasive species, this species needs to be closely monitored and protective measures must be immediately enacted. 

This species is distributed in the south-western Atlantic, restricted to eastern Brazil (Marceniuk and Menezes 2003) specifically in the Rio Doce (Espirito Santo State) and Rio Paraiba do Sul rivers (Rio de Janeiro State), and in the estuaries of these rivers. It has only been collected in the main channel, but never in the tributaries of these rivers. In the state of Espírito Santo, after more than 50 years without records of the species, recent fieldwork has revealed that the species is extinct at Lagoa Juparanã (type locality) but still can be found at Lagoa Nova in Linhares municipality (Marceniuk et al. 2019). Surveys must therefore be increased in order to evaluate the exact presence of this species.

This species was collected in Linhares, Espirito Santo in the Juparanã Lagoon (Rio Doce) in 1965 with 10 specimens collected. In the next three collections after 1965, no individuals were collected and it is now considered to be extinct in Juparanã. Other collections by Museum Mero Leitao for freshwater fishes in the wider region since did not record any individuals until 2017 when one male of 250 mm TL was recorded. This species is however poorly studied and there has never been a targeted research effort to determine population size and trends. Moreover, the species is still found at Lagoa Nova in Linhares municipality, Espírito Santo state and further south in the main channels of Rio de Janeiro. 

A decline is inferred as a result of ongoing threats, and a continuing decline in mature individuals is also inferred given local extinctions.

It is a benthopelagic species that lives in freshwater and estuarine waters. Marceniuk and Menezes (2007) described individuals from Espirito Santo and mention a maximum size of 35 cm.

The species may be seriously threatened due to degradation of its natural environment. The Rio Doce basin is historically impacted by diverse types of human actions for over three centuries, since the discovery of gold deposits at Villa Rica (Ouro Preto, Minas Gerais State). According to the National Water Agency (ANA 2009), the main economic activities developed in the basin have great potential for environmental degradation, such as mineral exploration (iron, gold, bauxite, manganese, limestone, etc.), industries (sugar and alcohol), livestock (dairy cattle and pigs), agriculture (coffee, sugarcane, cocoa, horticultural products, and cassava), silviculture (extensive eucalyptus plantations), electric power production, and introduction of alien fish species (Maceniuk et al. 2019). Mining and invasive species are thought to be the most significant threats.

This species has no known commercial importance nor is there a tradition of consumption of this species by riverine communities in the distribution area.

Fish fauna inventories, ecological studies, environmental education projects, and control of alien species are extremely necessary for the lower Rio Doce basin, especially for its lakes, which were not reached by the mudflow that entered through the main channel of the river in November 2015. The lakes and tributaries from the lower Rio Doce basin will possibly be responsible for the recolonization of the river channel and its impacted tributaries and its preservation and recovery are essential for the revitalization of the river basin and preservation of its aquatic species, including species, such as P. grandoculis.