Spirulina and Guppy Fry Growth

ISEF Category: Animal Sciences

Subcategory: Nutrition and Growth  ·  Difficulty: Intermediate  ·  Setup: School Lab  ·  Time: 1 to 2 Months

The Hook

Tiny fish can change color when their diet changes. That makes guppy fry a strong model for studying nutrition in living animals. You can ask whether spirulina powder helps them live longer, grow better, or show brighter color. The project connects fish food, health, and visible traits you can actually measure.

What Is It?

This project tests how adding spirulina powder to guppy fry food changes two things, survival and color expression. Survival tells you how many fry stay alive under each diet. Color expression tells you how strong or vivid their body color looks over time.

Spirulina is a blue-green microalga that people often mix into fish food. Think of it like a nutrient booster added to a basic recipe. Guppy fry are young fish, so they grow fast and can show diet effects sooner than adult fish. If the food changes their health, you may also see changes in how much orange, red, or green appears on their bodies.

Why This Is a Good Topic

This makes a strong science fair topic because diet, growth, and color all give you measurable data. You can compare groups with different spirulina levels and track clear outcomes. The project also connects to aquaculture, pet fish care, and animal nutrition, so the results matter outside your tank. A student can learn experimental design, animal care, and simple statistics without needing a university lab.

Research Questions

• How does spirulina supplementation affect guppy fry survival rate??
• What is the effect of different spirulina doses on guppy fry color intensity??
• Does spirulina mixed into fry food change growth rate compared with standard feed alone??
• To what extent does spirulina affect the proportion of fry that develop brighter orange or red pigmentation??
• Which feeding level of spirulina produces the best balance of survival and color expression??
• How does spirulina supplementation affect growth variability within a guppy fry group??

Basic Materials

• Guppy fry from the same breeding group.
• Matching aquarium tanks or divided tank compartments.
• Water conditioner for aquarium use.
• Standard guppy fry food.
• Spirulina powder labeled for food or aquarium use.
• Digital kitchen scale with 0.1 g accuracy.
• Aquarium thermometer.
• Water test strips or liquid test kit for ammonia, nitrite, nitrate, and pH.
• Fine mesh net or turkey baster for gentle handling.
• Phone camera with fixed settings.
• White background or light box for photos.
• Spreadsheet for recording survival, growth, and color scores.

Advanced Materials

• Dissecting microscope or high-resolution macro imaging setup.
• ImageJ for image analysis.
• Dissolved oxygen meter.
• Conductivity meter.
• Spectrophotometer for feed color or pigment extraction if available.
• Analytical balance.
• Controlled recirculating aquarium system.
• Microdiets or pellet mill for feed preparation.
• Water quality logging system.
• Statistical software for mixed-effects or survival analysis.
• Histology supplies if your lab approves tissue-level nutrition work.

Software & Tools

• ImageJ: Measures color area and brightness from standardized photos of each fry.
• Google Sheets: Organizes survival counts, growth data, and diet groups in one place.
• R: Runs survival curves, group comparisons, and simple models.
• Python: Automates image cleanup and color measurements if you want more advanced analysis.
• Canva Color Picker: Helps you compare representative color values from consistent images.

Experiment Steps

1. Define one diet factor you will change, such as spirulina level in the feed.
2. Decide how you will separate survival data from color data so each outcome stays measurable.
3. Plan matching control groups so your baseline diet is clear and fair.
4. Build a photo method that keeps lighting, background, and camera position the same each time.
5. Choose one growth metric and one color metric before you start, so you do not chase too many outcomes.
6. Set up a data table for repeated measurements and survival tracking across the whole trial.

Common Pitfalls

• Mixing the spirulina unevenly into feed, which makes each group eat a different actual dose.
• Photographing fry under changing light, which makes color scores drift from day to day.
• Using fry from different parent fish, which can hide diet effects behind genetics.
• Letting water quality vary between tanks, which can change survival more than the food does.
• Scoring color by eye without a fixed method, which makes the results hard to defend.

What Makes This Competitive

A stronger version of this project goes beyond a simple before-and-after comparison. You can test multiple spirulina levels, separate survival from pigmentation effects, and use a repeatable image analysis method instead of a visual guess. Strong controls matter here, especially matched age, water quality, and parent stock. Clear statistics and a thoughtful dose-response design can turn a basic aquarium study into a more serious research project.

Project Variations

• Test spirulina on fry from different guppy color strains and compare whether one strain responds more strongly.
• Compare spirulina powder with another natural pigment source, such as paprika or algae flakes, to see which food gives stronger color.
• Measure whether spirulina changes survival and color differently in male and female fry after the same feeding plan.

Learn More

• NIH PubMed: Search review articles on spirulina, fish nutrition, and carotenoids to find peer-reviewed background reading.
• NOAA Fisheries: Look for public resources on aquaculture feeding, water quality, and fish health.
• USDA National Agricultural Library: Search for fish nutrition and feed formulation resources in the government collection.
• Aquaculture: Search recent journal articles on ornamental fish nutrition, pigment supplementation, and fry growth.
• MIT OpenCourseWare: Use biology or data analysis course materials to review experimental design and statistics.