Invasive Species in USA Waterways - Part 35
To clarify, the Oscar fish is an invasive species of freshwater fish in the cichlid family. While, there are various types of Oscar fish, the three main Oscar Fish Types are the Tiger Oscar, Red Oscar and Albino Oscar. While, the Blue, Black, Florida, White, Green, Veil Tail and Lemon Oscars are mixes of the three main types of fish.
Furthermore, native to South America. But, a popular aquarium fish.
Invasive Species Definition
The definition of an invasive species is any species that is not native to our ecosystems and cause harm when introduced to the ecosystems. Furthermore, these may include amphibians, plants, insects, fish, fungus, bacteria and more. Further, impacts on the environment may cause economic loss or affect human health.
While, Invasive species tend to grow and reproduce quickly and spread aggressively with the potential to cause harm on the environment, economy or even human health. Therefore, given the label “invasive”.
Description of the Oscar Fish
While, the Astronotus ocellatus weighs approximately 3.5 pounds. Generally, reach 11 or 12 inches. But, may rarely exceed 14 to 15 inches.
Wild forms are generally darkly colored with yellow-ringed spots (ocelli) on the caudal peduncle and on the dorsal fin. Further, bright orange opercle margin and ventral parts of the lateral sides of the body.
While, these ocelli function to limit fin-nipping by piranhas in the Oscar fish natural native environments. Meanwhile, they can rapidly alter in coloration, facilitating ritualized territorial and combat behaviors amongst conspecifics.
Furthermore, male Oscars have dark blotches on the base of the dorsal fins. While, juvenile fish has a different coloration than the adults. Moreover, being striped with white and orange wavy bands and spotted heads.
Generally, have large mouths with thick lips. While, they have seven preopercular pores, the first gill arch is without lobe while gill rakers are short and thick with many denticles.
Furthermore, Oscars have 12 – 14 dorsal spines with 19 – 21 soft dorsal rays and 3 anal spines with 15 – 17 soft anal rays. While, the dorsal and anal fins bases are densely scaled with many branched rays.
Difference Types of Oscar Fish
|Characteristics||Tiger Oscar||Red Oscar||Albino Oscar|
|Color Form||Black, Red, Orange||Orange, Red||Red, White|
|Eye Color||Red Eye with Black Rim||Black with Orange Rim||Red with White Rim|
|Diet||Omnivore||Eats Anything and Everything||Omnivore|
|Water Temperature||72°F - 77°F||72 - 77°F||72°F - 77°F|
|Max Size of the Astronotus ocellatus||12 Inches||11 – 12 Inches||11 – 12 Inches|
|Temperament||Semi-Aggressive||Aggressive / Semi-Aggressive||Semi-Aggressive|
Biology of the Oscar Fish
While, the Oscar is a very intelligent tropical fish renowned for their personalities.
Meanwhile, a freshwater Tropical fish living in shallow slow-moving white-water habitats in canals and ponds with a mud or sand substrate. Generally, sheltering under submerged branches.
While, ideal conditions include pH ranges between 6.0 and 8.0. and water temperatures ranging from 71.5°F to 77°F. However, the Oscar Fish does not tolerate cold water temperatures, with lower lethal limits for the species being 55.22°F.
Generally, the Oscar Fish is an omnivore feeding on vegetation, crayfish, worms, insect larvae and small fry. However, not fussy eaters and readily eat other forms of sustenance.
The Oscar is widely regarded as sexually monomorphic with males and growing more quickly than females. While, the species reaches sexual maturity around one year of age. Further, reproduction continues for 9 – 10 years.
While, the frequency and timing of spawning may be related to the occurrence of rain. Both males and female Oscar fish clean a suitable spawning site. Generally, on a flat rock or branch or excavate a circular nest in shallow waters.
While, depositing thousands of eggs which are guarded by the parents. Generally, eggs have in 3 to 4 days and the parents move the fry to a shallow pit in the sand where they stay for 6 to 7 days. Until they become free swimming.
Distribution of the Astronotus ocellatus
Generally, found in South America including Peru, Ecuador, Colombia, Brazil, French Guiana, the Amazon River Basin along the Amazon, Icá Negro, Solimōes and Ucayali River systems. As well as, in the Approuague and Oyapock River drainages. Furthermore, the Oscar fish also occurs in China, Australia, Africa and the United States.
Effect on the Ecosystem
However, potentially competes with native fish for food and spawning areas. Especially affecting the sunfish. While, the Oscar Fish is a predator and further reduces numbers of native fish and invertebrates.
Introduction to the USA of the Oscar
The first records of the Oscar fish in Florida was due to deliberate stocking from aquariums. While, attempts were made to popularize the species as a sport fish.
As a result, has led to anglers farther releasing this fish into other water sources. Furthermore, this fish can currently be found in Florida, Hawaii and Puerto Rico.
In short, Oscar fish in the United States, especially in Florida are presumed to be contaminated with mercury. Therefore, limited consumption is recommended.
Conservation of the Astronotus ocellatus
The Oscar Fish was readily introduced to various parts of the United States. However, after numerous attempts by the fishery industry to get this species to establish itself. The only populations that have readily established and reproduced has been the population in Florida.
Anglers, have further spread this species to various water sources, where it was not otherwise introduced. Therefore, angling of this species, being a sport fish, is highly prized. However, good size Oscar fish can be eaten in moderation due to mercury contamination. While, this fish is also a popular aquarium fish. Therefore, looked after by the aquarium trade.
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