The growth of betta fry encompasses multiple aspects such as body size changes, body color development, and environmental adaptability. Their growth cycle typically lasts 4-6 months, with the following key growth characteristics:
I. Growth Cycle and Stage Characteristics
Betta fry take 4-6 months to develop from hatched eggs to adult fish, and their growth process can be divided into four critical stages:
Egg Stage to Free-Swimming Stage (0-15 Days)
Newly hatched fry are only about 1 mm in body length and cling to bubble nests or the tank walls. The male betta stirs the water flow with its pectoral fins to deliver oxygen to the fry.
Notes: No feeding is required at this stage, as the fry absorb nutrients from their yolk sacs. Feeding too early can lead to water quality deterioration and even cause the male betta to prey on the fry.
First Feeding Stage (15-30 Days)
After the fry start swimming freely, they need to be fed infusoria, "Red Heart A" brine shrimp, or egg yolk water as their initial food.
Growth Data: By day 25, the fry can reach a body length of 1 cm, mainly relying on brine shrimp and supplementary feed for nutrition.
Sub-Adult Stage (1-3 Months)
The fry's body length grows to 1.5-2.5 cm, and they gradually develop color after entering the "flesh-color stage".
Feed Adjustment: Chopped bloodworms, tubifex worms, or daphnia can be introduced, but the feeding amount must be controlled to avoid indigestion.
Environmental Management: Maintain the water temperature at 26-28°C and change 1/3 to 1/2 of the water daily to prevent excessive ammonia nitrogen levels.
Sexual Maturity Stage (4-6 Months)
The fry reach a body length of 4-5 cm. Male bettas begin building bubble nests, and female bettas develop breeding stripes.
Breeding Recommendation: It is advisable to wait until the fry reach a body length of 4 cm and then delay breeding until they are 5-6 months old. This avoids health loss caused by premature breeding.
II. Variety Differences and Growth Rate
Different varieties of betta fry exhibit differences in growth rate:
Thai Bettas: Benefiting from their tropical genes, they can reach sexual maturity in 3-4 months. Under a water temperature of 26-30°C, their metabolism is vigorous, with a daily weight gain of up to 2.8 mg.
Chinese Bettas (e.g., round-tailed, fork-tailed bettas): They adapt well to temperature fluctuations in their native environment and have a steady growth rhythm, taking 4-5 months to mature. Improved varieties may even take up to 6 months.
III. Impact of Environmental Factors on Growth
Water Temperature: 25°C is the optimal growth temperature. Below 20°C, growth slows down by 40%, and sexual maturity is delayed to 220 days.
Water Quality: Maintain slightly acidic soft water (pH 6.5-7.5) and avoid using alkaline regulators. Ammonia nitrogen levels must be controlled below 0.2 mg/L.
Lighting: Moderate lighting from LED lights is sufficient. Excessive light can cause algae blooms, which affect water quality.
Space: Larger tanks promote faster growth. It is recommended to provide 5-10 liters of water per fry and install a filter to maintain clean water.
IV. Feed and Nutrition Management
First Feeding Food: Infusoria, "Red Heart A" brine shrimp, or egg yolk water. Feed 4-6 times a day, with each feeding amount sufficient for the fry to finish within 5-8 minutes.
Sub-Adult Stage Feed: Chopped bloodworms, tubifex worms, or daphnia, supplemented with a small amount of brine shrimp. Feed 2-3 times a day.
Sexual Maturity Stage Feed: 2-3 bloodworms per meal, 3 times a day. Provide brine shrimp 1-2 times a week to vary the diet.
V. Common Issues and Solutions
Water Quality Deterioration
Symptoms: Fry surface for air (gasping) and reduced appetite.
Solution: Change 1/3 of the water daily, use a sponge filter (air-driven filter), and keep ammonia nitrogen levels below 0.2 mg/L.
Slow Growth
Symptoms: Slow body length growth and dull body color.
Solution: Check if the water temperature is below 25°C, adjust the type of feed, and increase the amount of live food fed.
Disease Prevention
Ich (White Spot Disease): Caused by sudden temperature changes. Maintain stable water temperature and treat with methylene blue baths.
Fin Rot: Caused by water pollution. Change water promptly and treat with yellow powder (nitrofurazone) baths.