Oscar fish have moderate care needs. Replicating the oscar fish’s freshwater tropical habitat and varied omnivorous diet is easy. However, because of the oscar fish’s aggressive tendencies, the fish requires extra care when housing with other fish species.

A large tank, consistent water parameters, and a strong water flow are the three most important tank requirements for oscar fish. You should feed oscar fish a healthy, varied diet of live foods, pellet foods, and plant matter.

Habitat and Tank Requirements
In the wild, oscar fish are found in the freshwater Amazon and Orinoco Rivers and tributaries. The oscar fish’s natural habitat is one of the most biodiverse environments on the planet, and you should aim to replicate this habitat in the aquarium, with warm, tropical waters and varied plant species.

To recreate the oscar fish’s natural habitat, fill a large, freshwater tank and introduce a soft, sandy substrate with debris, vegetation, and rocks scattered on top.

Tank decorations like caves and plants like Java fern and Java moss can be used to replicate the rocky riverbed and underwater greenery.

Oscar fish enjoy digging in the substrate and rearranging the tank, so plants should be hardy and firmly rooted, and tank decorations should be firmly fixed in place.

Tank Conditions
The desired tank conditions for oscar fish are listed below:

Oscar fish can’t survive in temperatures below 55ºF, so make sure water temperature is consistent.

pH consistency is also important — oscar fish need a neutral pH, and aren’t used to acidic or alkaline waters.

Aside from water parameters, providing enough space for oscar fish to swim in and claim their own territories will benefit the fish’s long-term happiness and health.

Disease
There are several diseases that commonly affect oscar fish: hole in the head, Ich, and fin rot.

Hole in the Head
Hole in the head is a common freshwater disease caused by a parasite called hexamita. The disease is so-called because it leads to head lesions. It can also cause lesions on the fish’s torso, a loss of appetite, and color fading.

Prevent hole in the head by maintaining consistent water parameters. Reverse the disease by improving water quality and making sure the fish gets plenty of vitamin and mineral supplementation.

Ich
Ich is caused by a protozoan parasite called Ichthyophthirius multifiliis. This disease is commonly brought into an aquarium when new plants, live foods, and new fish are introduced. Symptoms of Ich include reddening of the fins, white spots on the gills and fins, and flashing (when fish rub their bodies against rough objects).

Treat Ich by adding one tablespoon of salt for every two gallons of water and increasing the temperature of the tank by a couple of degrees to speed up the lifecycle of the parasite.

Fin Rot
Caused by a bacterial infection, fin rot occurs when oscar fish are stressed by poor water quality, overcrowding, or low oxygen levels. Fin rot is characterized by tattered or blackened fins with a milky appearance, lethargy, and loss of appetite.

Prevent fin rot by eliminating environmental stressors. Treat oscar fish with fin rot with antibiotics prescribed by your veterinarian.