Ruby Rasbora - Paedocypris progenetica : Complete Fish Profile & Care Guide
Table of contents
Introduction
Prior to 2012, the title of the world's smallest known vertebrate belonged to the Ruby Rasbora (Paedocypris progenetica) until the discovery of the tiniest frog. Nonetheless, the Ruby Rasbora retains its distinction as the smallest freshwater fish capable of thriving in a home aquarium. Due to their delicate nature and specific water requirements, these fish are considered expert-level and are not suitable for beginners in the hobby. It is essential to exercise caution during the acclimation process, as Ruby Rasboras are intolerant of elevated nitrates and fluctuations in water chemistry.
To foster a sense of security, keeping a decent-sized group of 12 or more Ruby Rasboras is recommended, as they can be quite timid. While an ideal setup consists of a species-only aquarium, if other aquatic species are intended to be kept with them, it is crucial to ensure that these companions are small and exhibit a peaceful temperament. Neon Tetras, Micro Rasboras, small Caridina and Neocaridina shrimps are examples of suitable tankmates for Ruby Rasboras.
Small aquariums with dense vegetation provide an optimal environment for Ruby Rasboras. Mature water, abundant plant growth, and the presence of floating plants to diffuse light and create numerous hiding spots are essential elements to consider. Broad-leaved plants can encourage spawning behaviour. Filtration should be efficient, while water movement should be gentle to accommodate the delicate nature of these fish.
The use of reverse osmosis (RO) water, filtered through aquarium peat to lower pH, is highly recommended. Additionally, including dried Indian almond leaves or blackwater extract can be beneficial. These additives release tannins, resulting in a natural tea-like water colouration. This characteristic does not harm the fish but enhances their vibrant colours.
The Ruby Rasbora exhibits a slender and somewhat transparent body, featuring distinctive pelvic fins with clutching pads that males utilize during mating. During spawning, males develop a crystal red colouration and display a red mark on their heads, serving as a blinking light to attract females to the spawning site.
Ruby Rasbora Photos
Sexual Dimorphism
Distinguishing between male and female Ruby Rasboras is a relatively uncomplicated task. Male individuals exhibit distinct pelvic fin modifications, characterized by hypertrophied muscles and a keratinized pad positioned in front of the fin. In contrast, the pelvic fins of females are rudimentary or even absent, and they tend to grow larger in size compared to males.
Quick Facts
| Scientific Name | Paedocypris progenetica |
|---|---|
| Year Described | 2006 |
| Other Names | Indonesian Superdwarf fish, Sumatran Miniature Cyprinid |
| Kingdom | Animalia |
| Classification | Actinopterygii |
| Order | Cypriniformes |
| Family | Cyprinidae |
| Genus | Paedocypris |
| Origins | Indonesia |
| Max Size | 1 cm |
| Temperament | Peaceful |
| Aquarium Level | Middle |
| Difficulty | Intermediate - Advanced |
| Shoaling | Yes |
| Best kept as | Groups 10+ |
| Diet & Feeding | Omnivore |
| Reproduction | Egg Depositor |
| Average Lifespan | Up to 1 Year |
Water Parameters
| Water Type | Freshwater |
|---|---|
| pH | 3.0 - 4.0 |
| GH | 0 - 5 |
| ℉ | 80 - 89 |
|---|---|
| ℃ | 26 - 31 |
Natural Habitat
Endemic to Indonesia, specifically the peat swamp forests of Sumatra and Bintan, Ruby Rasboras have a limited distribution within these regions. They primarily reside in the lower portion of the water column, occupying deeper and cooler layers of water. These fish exhibit a preference for shaded areas with reduced light intensity. Their diminutive size allows them to adapt to small water bodies, such as puddles that persist after periods of drought. However, their specialized habitats and restricted ranges make them particularly vulnerable to habitat loss.
The Ruby Rasboras face a significant threat of extinction due to the destruction of their natural habitats. As their unique ecosystems suffer from habitat degradation and loss, their population numbers dwindle. Urgent conservation measures are imperative to protect these remarkable fish and mitigate the risks posed by ongoing habitat destruction.
Breeding
The successful breeding of the Ruby Rasbora in captivity has been achieved on only a few occasions, making it an engaging and challenging endeavour suitable for experienced hobbyists. In order to establish their respective breeding territories, male Ruby Rasboras swim beneath broad leaves when they are ready to spawn. Minor scuffles may ensue among rival males competing for preferred spawning sites. Notably, such behaviours are commonly observed when the morning sunlight illuminates the aquarium glass or when the tank lights are initially switched on.
Once spawning territories are secured beneath the leaf, the male fish inverts itself, positioning its belly towards the underside of the leaf. After a brief interval, often in the presence of nearby females, the male detaches himself from the leaf and returns to a swimming position before swiftly returning to his place beneath the leaf. He may occasionally move up and down while maintaining this position, followed by a short interval before re-attaching himself to the leaf and resuming normal swimming behaviour. This rhythmic motion is repeated every few seconds, with the male positioning an iridescent spot on his head towards the female. A receptive female eventually joins the male beneath the leaf, inverting herself and positioning next to him. However, the precise details of the mating process remain largely unknown, as it occurs exceptionally quickly.
On the undersurface of the leaf, spherical and translucent adhesive eggs are laid, which typically hatch within approximately 30 hours, influenced by the prevailing temperature. The newly hatched larvae are minuscule and immobile, attaching themselves to the leaf's undersurface or aquarium glass. Raising the tiny fry presents significant challenges due to their specific dietary requirements, necessitating microscopic food sources.
Diet & Feeding
Ruby Rasboras have specific dietary requirements that necessitate the provision of small-sized food options. It is recommended to offer them a variety of tiny foods, including decapsulated brine shrimp eggs, baby brine shrimp, rotifers, microworms, crushed flakes, and micropellets. These nutritionally diverse offerings will help ensure the optimal nutritional intake for Ruby Rasboras and promote their overall health and well-being.
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