Stocking Guide: Choose Compatible Fish

The Golden Rule: Research Before Purchase

Impulse buying is the leading cause of "New Tank Syndrome." Fish are not decorations; they are animals with specific metabolic, social, and environmental requirements.

• The Trap: A juvenile Oscar looks cute at 2 inches but grows to the size of a dinner plate (12+ inches) and produces massive waste.
• The Solution: Never buy a fish without knowing its Adult Size, Diet, and Temperament.

Architectural Compatibility

Tank Volume vs. Footprint

Volume buffers chemistry, but footprint determines activity.

• Active Swimmers: Fish like Zebra Danios or Neon Tetras are high-energy athletes. Even if they are small, they require a Long tank (minimum 20-gallon Long) to sprint back and forth. Putting them in a tall, narrow hexagon tank causes stress and muscle atrophy.
• Territorial Species: Cichlids and Gouramis claim physical territory on the substrate. A "20-gallon High" has less floor space than a "20-gallon Long," meaning fewer territories and higher aggression.

The Vertical Stratification

To maximize space and minimize conflict, choose fish that occupy different water columns.

• Top Dwellers: Hatchetfish, Guppies (surface feeders).
• Mid-Water: Tetras, Rasboras, Rainbowfish (schooling swimmers).
• Bottom Dwellers: Corydoras, Loaches, Plecos (scavengers).
• The Benefit: By spreading fish out vertically, you reduce visual clutter and competition for space.

Social Engineering

Schooling Requirements (Safety in Numbers)

Most beginner fish (Tetras, Rasboras, Corydoras) are prey animals. They rely on the "School" for security.

• Minimum School Size: 6+ individuals of the same species.
• The Stress Response: If you buy only 2 or 3, they will live in a state of chronic cortisol (stress) elevation. They will hide, lose color, and their immune systems will collapse, leading to disease.
• AI Alert: The Residents AI will flag a "Social Stress" warning if you input fewer than 6 of a schooling species.

Aggression & Compatibility

• Community Fish: Peaceful species (Guppies, Mollies, Platies) that ignore neighbors.
• Semi-Aggressive: Fin-nippers (Tiger Barbs, Serpae Tetras). These will shred the long fins of Bettas or Angelfish.
• Aggressive: Territorial predators (Cichlids). These will kill anything they can fit in their mouth or that enters their zone.
• The AI Check: The App cross-references your potential buy list. If you try to add a Tiger Barb to a tank with a Betta, the Residents AI will block the selection with an "Incompatible: Fin Nipping Risk" alert.

The "Centerpiece" Fish

Many aquarists want one "star" fish.

• Good Candidates: A single Honey Gourami, a Betta (in a community of peaceful bottom dwellers), or a pair of Dwarf Cichlids (Apistogramma).
• Bad Candidates: A "Common Pleco" (grows to 18 inches) or a "Red Tailed Shark" (becomes highly aggressive with age).

Environmental Parameters

Temperature Gradient

• Tropical: Requires a heater (75°F–80°F). Includes Betta, Tetras, Guppies.
• Coldwater: Prefers unheated tanks (60°F–70°F). Includes Goldfish, White Cloud Minnows.
• The Mismatch: Keeping Goldfish (Cold) with Tetras (Tropical) ensures one species is always thermally stressed. The Residents AI will flag this as a "Thermal Incompatibility."

Substrate Requirements

Bottom dwellers interact directly with your floor.

• Corydoras: These catfish have sensitive barbels (whiskers) used to hunt for food. Sharp gravel will erode these barbels, leading to infection and starvation. Sand is mandatory.
• Loaches: Many loaches like to burrow. Provide soft substrate or hiding tubes.

Using the Residents AI for Validation

Do not guess. Simulate your population before you leave the house.

The Residents Tab Workflow

1. Open the "Residents" Tab: This is your census tool.
2. Input Your Wishlist: Add the species you want (e.g., "10 Neon Tetras," "1 Betta," "6 Corydoras").
3. Analyze the Data:

• Stocking Level: The AI calculates if your tank volume is sufficient.
• Social Check: It warns you if school sizes are too small (e.g., "Increase Neon Tetra count to 6+").
• Conflict Check: It identifies predation risks (e.g., "Betta may attack Neon Tetras").

The Bioload Calculation (75% Rule)

"Bioload" is the metabolic cost of a fish.

• The Myth: "1 inch of fish per gallon." This is dangerous. A 10-inch Oscar produces 50x more waste than ten 1-inch Tetras.
• The Reality: The Residents AI calculates the actual metabolic weight of the fish against your filtration capacity.
• Target: Aim for 75% Stocking Capacity. Leaving 25% "headroom" ensures your system can handle an accidental overfeeding or a missed water change without crashing.

Connecting to the Health Lab

Once stocked, the Residents data feeds directly into the Health Lab to predict maintenance.

• Nitrate Forecast: The Lab estimates how fast Nitrate will rise based on the metabolic rate of the specific fish you entered.
• Filter Clogging: It predicts how often you need to rinse your sponge based on the physical waste production of your stock list.
• The Benefit: A tank stocked with 20 Guppies will generate a different maintenance schedule than a tank stocked with 1 Goldfish, even if they have the same biomass. The AI adjusts for this biology.