Aquatic snake feeding mainly on fish. It may be aggressive when handled or threatened. It never attacks without a good reason in fact it tends to escape. It has no poison, but the bite may be nasty. In this area it is more common than its relative H. leopardinus. Anyway these individuals were seen at the time of the 2016 flood, which might indicate they arrived on water hyacinth mats.
Robust head, big eyes and dark back. The eyes and the nostrils to the top of the head evidence its aquatic habit.
Difference with H. leopardinus
H. infrataeniatus has a yellow belly with one or two parallel black lines in the middle and/or several dark spots uniformly distributed. Besides two lighter longitudinal lines run along the back. The yellow colouring reaches the gular area (throat) where it is crossed by transversal black stripes. 
H. leopardinus thas a red belly (also known in Spanish as "red-bellied") with transversal black lines. On the back circular spots contrast all along the sides, which gives the epithet leopardinus. Gular area is yellow.
The confusion arises because gular areas are yellow in both species. But the pattern of the upperparts shows the distinctive features. H. infrataeniatus juveniles may show reddish colouring too

Juvenile

Rufescent tiger-heron