Paracheirodon simulans
Green Neon Tetra
Scientific Classification
Kingdom:Animalia
Phylum:Chordata
Class:Actinopterygii
Order:Characiformes
Family:Characidae
Genus:Paracheirodon
Species:simulans
IUCN Status:Not Evaluated
Quick Stats
Difficulty
Medium
Environment
Freshwater
Temperature
23°C - 27°C
pH Level
4 - 6.5
Water Hardness
18 - 90 ppm
Lifespan
5 years
Origin
South America
Adult Size
20 - 25 cm
Diet
Omnivore
Creature Type
Fish
TDS
150 ppm
Water Flow
Low Flow
Aquarium Building Information
Minimum Tank Size
40L
Swimming Zone
top, middle
Minimum School Size
6+
Oxygen Consumption
Low
Waste Production
Low
Metabolism Rate
Low
Activity Level
Active
Feeding Frequency
Daily
Food Types
Flakes
Pellets
Frozen Food
Live Food
Freeze Dried
About This Species
Basic Description
A small and vibrant shoaling fish from South America, the Green Neon Tetra brings dazzling color and energetic activity to well-maintained soft, acidic aquariums. These peaceful fish are known for their brilliant, electric blue-green horizontal stripe that shimmers under aquarium lighting. As very active swimmers, they thrive in groups and should always be kept with several of their own kind to feel secure and display their best colors and natural behaviors. They are an excellent choice for a peaceful community tank alongside other small, gentle species. Although they are quite hardy once acclimated, their need for specific water chemistry—notably soft and acidic conditions—makes them a better fit for aquarists who have some experience managing water parameters. They are omnivores and will readily accept a variety of high-quality prepared foods, making feeding straightforward. Their small adult size means they contribute minimally to the tank's waste load, but they still require a well-filtered environment with gentle water movement to replicate their native habitat. Their relatively long lifespan makes them a rewarding, long-term addition to a thoughtfully planned aquarium.
Detailed Description
Paracheirodon simulans, a captivating characin from the blackwater tributaries of South America, is a species for the aquarist who appreciates creating a true biotope. Its natural habitat consists of slow-moving, tannin-stained waters that are exceptionally soft and acidic, a condition that must be closely replicated in captivity for the fish to thrive. A successful setup often involves the use of reverse osmosis (RO) water remineralized to a very low general hardness, with a substrate of fine sand and an abundance of driftwood, catappa leaves, and other botanicals. These additions release humic substances that help lower the pH and buffer it at the required acidic level, while also providing a sense of security for the fish. Dense plantings with species that tolerate low-light and soft water, complemented by floating plants to diffuse overhead lighting, will further mimic their preferred environment and encourage natural behavior. Socially, this species is a quintessential shoaling fish. While a minimum group is often cited, they truly come alive in larger aggregations of a dozen or more. In a sizable group, their synchronized, darting movements are mesmerizing, and any intra-species squabbling is spread harmlessly throughout the shoal. Their peaceful temperament makes them ideal for community aquariums, provided their tank mates can also tolerate the soft, acidic conditions and are not large enough to view them as prey. Suitable companions include various dwarf cichlids, pencilfish, and smaller bottom-dwelling catfishes. A varied, omnivorous diet is essential for maintaining their health and vibrant coloration. High-quality micro-pellets and crushed flakes should form the staple, but this must be supplemented regularly with frozen or live foods such as daphnia, cyclops, and baby brine shrimp. Their active nature means they are constantly exploring the upper and middle levels of the water column, adding perpetual motion to the aquascape.
Scientific Description
Paracheirodon simulans is a small characid native to the upper Orinoco and Rio Negro basins in South America. It inhabits oligotrophic blackwater environments characterized by extremely low conductivity, negligible mineral content, and a highly acidic pH, often resulting from a high concentration of dissolved humic and fulvic acids from decaying terrestrial vegetation. Its physiological adaptations to these specific conditions are significant; the species demonstrates a high degree of specialization in its osmoregulatory functions, which makes it intolerant of hard, alkaline water with high total dissolved solids. In a captive setting, failure to replicate these parameters can lead to chronic stress, compromised immune function, and organ failure. The fish's body shape is fusiform, an elongated and streamlined morphology that is hydrodynamically efficient for its active swimming behavior in the low-flow environments it prefers. Its iridescent lateral stripe is a key feature, produced by light-reflecting crystalline structures within specialized cells called iridophores. This is believed to function in intraspecific communication, facilitating school cohesion in the dimly lit, tannin-stained waters of its habitat. Behaviorally, P. simulans exhibits obligate shoaling, an anti-predator defense mechanism that also plays a role in foraging and reproduction. The species has a low metabolic rate and corresponding low oxygen consumption and waste production, resulting in a minimal bioload relative to its size. However, due to its sensitivity to nitrogenous waste, pristine water quality maintained through consistent filtration and water changes is paramount. Its IUCN Red List status as 'Not Evaluated' (NE) indicates a lack of comprehensive population studies in its natural range, highlighting the importance of sustainable collection practices and captive breeding efforts.
Breeding Description
Successfully breeding Paracheirodon simulans is a challenging endeavor that demands meticulous attention to detail and a dedicated setup, separate from a community aquarium. The primary difficulty lies in replicating the precise water chemistry that triggers spawning. A dedicated breeding tank of around 20-40 liters is sufficient. This tank should be sterilized and maintained under very dim lighting or kept in darkness until the spawning attempt. The water must be exceptionally soft, with a general hardness of virtually zero, and highly acidic. Achieving these conditions almost always requires the use of reverse osmosis (RO) or deionized (DI) water, often filtered through peat moss or supplemented with blackwater extracts to establish the necessary environment. Filtration should be gentle, typically an air-driven sponge filter, to avoid harming the delicate eggs and fry. To prepare for spawning, condition a group of healthy, mature adults by separating males and females if possible. Provide a rich diet of live and frozen foods for several weeks. Sexing these fish can be difficult, but mature females are generally fuller-bodied with a more rounded abdomen compared to the slimmer, more streamlined males. Once conditioned, select the most robust pair or a small group with a ratio of two males to one female and introduce them into the prepared breeding tank in the evening. Spawning usually occurs in the early morning hours. The fish are egg-scatterers and will deposit their adhesive eggs among spawning mops, fine-leaved plants like Java moss, or over a mesh grid placed on the tank bottom. The parents provide no care and will readily consume their own eggs, so they must be removed immediately after spawning is complete. The eggs are light-sensitive and will hatch in approximately 24-36 hours. The fry will become free-swimming a few days later after absorbing their yolk sacs. At this stage, they require microscopic foods such as infusoria, followed by newly hatched brine shrimp as they grow.
