---
name: aquarium-keeper
description: |
  Guide to freshwater aquarium keeping including tank setup, nitrogen cycle, stocking, water parameters, planted tanks, aquascaping styles, maintenance, disease prevention, and fish compatibility. Use when the user asks about aquarium keeper or needs help with related topics. Do NOT use for unrelated domains or when a more specialized skill exists.
license: Apache-2.0
metadata:
  author: foundry-skills
  version: "1.0.0"
  tags: "pet-care guide step-by-step"
  category: "hobbies-crafts"
  subcategory: "outdoor-recreation"
  depends: ""
  disclaimer: "none"
  difficulty: "beginner"
---

# Aquarium Keeper

## When to Use


## Process

1. **Gather requirements.** Ask the user clarifying questions about their specific context, goals, constraints, and experience level.

2. **Analyze the situation.** Review the information provided and identify key factors, challenges, and opportunities relevant to aquarium keeper.

3. **Develop the framework.** Create a structured approach tailored to the user's needs, incorporating best practices and domain-specific considerations.

4. **Deliver actionable output.** Present specific, implementable recommendations with clear rationale, timelines, and success criteria.

5. **Address edge cases.** Proactively identify potential issues, alternative approaches, and contingency plans.

**Use this skill when:**
- User needs guidance on aquarium keeper
- User asks about aquarium keeper best practices or techniques
- User wants a structured approach to aquarium keeper

**Do NOT use this skill when:**
- A more specialized skill exists for the specific subtopic
- The request is outside the scope of aquarium keeper

## Questions to Ask First

Before recommending a setup:

1. Have you kept fish before? (Never / Had a goldfish / Some experience / Experienced)
2. What size tank are you considering? (5 gal / 10-20 gal / 30-55 gal / 75+ gal)
3. What type of fish interest you? (Colorful community, single centerpiece, shrimp, planted tank)
4. Where will the tank be placed? (Room, surface it will sit on, access to electrical outlets)
5. What is your budget? ($50-100 / $100-300 / $300-700 / $700+)
6. How much time can you spend on maintenance? (10 min/week / 30 min/week / 1+ hour/week)
7. Do you have children or pets that might interact with the tank?
8. Are you interested in live plants?
9. How important is the aesthetic/design aspect to you?
10. Are you aware that new tanks need to "cycle" before adding fish? (This is critical)

## Tank Selection and Setup

### Tank Size Guidelines
- **Bigger is better for beginners**: Larger water volume is more stable and forgiving of mistakes
- **Minimum recommended**: 10 gallons for most beginners (5 gallons for experienced with nano fish or shrimp only)
- **20 gallons**: Sweet spot for beginners - stable, affordable, good stocking options
- **55+ gallons**: Wide variety of fish, very stable, but heavier and more expensive

### Weight Considerations
- Water weighs 8.3 lbs per gallon
- A 20-gallon tank with water, substrate, and equipment weighs ~225 lbs
- A 55-gallon tank weighs ~625 lbs
- Ensure your stand and floor can support the weight
- **Never place a tank on furniture not rated for the weight**

### Essential Equipment
- **Tank**: Glass or acrylic (glass is more scratch-resistant, acrylic is lighter)
- **Filter**: Rated for your tank size or larger
  - Hang-on-back (HOB): Easy, affordable, good for beginners (AquaClear, Marineland Penguin)
  - Canister filter: Best filtration, quieter, more expensive (Fluval, Eheim)
  - Sponge filter: Gentle, great for shrimp tanks and breeding, powered by air pump
- **Heater**: Most tropical fish need 76-80F. Get adjustable heater rated for your tank (5 watts per gallon rule). Brands: Eheim Jager, Fluval, Aqueon Pro.
- **Thermometer**: Verify heater is working correctly ($3-8)
- **Lighting**: LED is standard. Basic LED for fish-only, plant-specific LED for planted tanks (Fluval Plant 3.0, Nicrew)
- **Substrate**: Gravel (easy, inert), sand (natural look), planted tank soil (Fluval Stratum, ADA Amazonia for plants)
- **Water conditioner**: Dechlorinates tap water. Seachem Prime is the standard ($5-10)
- **Test kit**: API Freshwater Master Test Kit ($25) - tests ammonia, nitrite, nitrate, pH. ESSENTIAL.

### Setup Process
1. Place tank on level, sturdy surface (use a leveling mat if surface is uneven)
2. Rinse substrate thoroughly (until water runs clear)
3. Add substrate to tank (1-2 inches for fish-only, 2-3 inches for planted)
4. Install filter, heater, and thermometer (do not plug in yet)
5. Add hardscape: Rocks, driftwood (arrange before filling with water)
6. Fill tank slowly (pour onto a plate to avoid disturbing substrate)
7. Add water conditioner (dose for full tank volume)
8. Turn on filter, heater, and lights
9. **DO NOT ADD FISH YET** - the tank must cycle first

## The Nitrogen Cycle (Most Important Concept)

### What Is Cycling?
Fish produce ammonia (toxic). Beneficial bacteria convert ammonia to nitrite (also toxic), then to nitrate (much less toxic). These bacteria must colonize your filter before the tank is safe for fish. This takes 4-8 weeks.

### The Cycle Steps
```
Fish waste / Food decay --> AMMONIA (NH3) [toxic at any level]
                              |
                    Nitrosomonas bacteria
                              |
                           NITRITE (NO2) [toxic at any level]
                              |
                    Nitrospira bacteria
                              |
                           NITRATE (NO3) [safe up to ~40 ppm, removed by water changes]
```

### Fishless Cycling (Recommended Method)
1. Set up tank completely (filter running, heater on)
2. Add ammonia source: Pure ammonia (Dr. Tim's Ammonium Chloride) to 2-4 ppm
3. Test daily with API test kit
4. Week 1-2: Ammonia remains high, nitrite at 0
5. Week 2-4: Ammonia drops, nitrite spikes
6. Week 4-8: Nitrite drops, nitrate appears
7. **Cycle is complete when**: Ammonia and nitrite both read 0 ppm within 24 hours of adding ammonia
8. Do a large water change (50-80%) to reduce nitrate before adding fish
9. Add fish gradually (not all at once)

### Speeding Up the Cycle
- Use established filter media from an existing tank
- Bottled bacteria (Seachem Stability, Fritz TurboStart 700) - helps but not instant
- Keep temperature at 80-82F (bacteria grow faster)
- Keep ammonia present but not above 4 ppm (too high kills the bacteria you are growing)
- Never let ammonia or nitrite reach 0 during cycling (bacteria starve)

### Fish-In Cycling (Emergency / Not Recommended)
- If fish are already in the tank, the cycle must happen with them present
- Test water DAILY
- Water change immediately if ammonia or nitrite exceeds 0.25 ppm (25-50% change)
- Use Seachem Prime to detoxify ammonia temporarily (re-dose every 48 hours)
- This is stressful for fish and can cause illness or death

## Stocking Guide

### General Stocking Rules
- **One inch of fish per gallon** is a rough starting point (does not account for fish shape, bioload, or activity level)
- Better approach: Research specific species' space requirements
- Start with 3-5 hardy fish, add more after 2-3 weeks
- Never add more than 3-5 fish at a time (prevents ammonia spikes)

### Beginner-Friendly Fish

**Community Tank Favorites**:
- **Neon Tetra**: Schooling (6+ required), peaceful, colorful, small. Temp: 72-78F
- **Corydoras Catfish**: Bottom dwellers, peaceful, active, social (6+ required). Temp: 72-79F
- **Guppies**: Colorful, active, breed readily, hardy. Temp: 72-82F
- **Platy**: Peaceful, colorful, easy, livebearers. Temp: 70-80F
- **Honey Gourami**: Peaceful centerpiece, beautiful, one per tank or pair. Temp: 72-82F
- **Cherry Barb**: Peaceful, colorful, schooling. Temp: 73-81F

**Bottom Dwellers**:
- **Corydoras** (various species): Must have sand or smooth substrate (barbels are sensitive)
- **Otocinclus**: Tiny algae eaters, delicate, need established tank, group of 6+
- **Kuhli Loach**: Eel-like, hides during day, active at night, needs hiding spots

**Algae Crew**:
- **Nerite Snails**: Best algae eaters, cannot reproduce in freshwater
- **Amano Shrimp**: Excellent algae eaters, peaceful, community-safe
- **Mystery Snails**: Interesting behavior, multiple colors, can reproduce

### Fish to Avoid as a Beginner
- **Common Pleco**: Grows to 18-24 inches, needs 100+ gallon tank
- **Bala Shark**: Grows to 12+ inches, schooling, needs 125+ gallons
- **Oscar**: Grows to 14 inches, aggressive, needs 75+ gallons
- **Chinese Algae Eater**: Becomes aggressive with age, attacks other fish
- **Goldfish**: Need cold water (65-72F), massive bio-load, 20+ gallons per fish (not tropical community fish)

### Fish Compatibility
- Match temperature requirements
- Match temperament (do not mix aggressive with peaceful)
- Match water flow preferences
- Provide appropriate tank mates for schooling fish (6+ of same species)
- Avoid fin nippers with long-finned fish
- Research adult size, not pet store juvenile size
- Male-to-female ratios matter for livebearers (1 male : 2-3 females minimum)

## Water Parameters

### Key Parameters and Targets
| Parameter | Ideal Range | Testing Frequency |
|-----------|------------|-------------------|
| Ammonia (NH3) | 0 ppm | Weekly (daily during cycling) |
| Nitrite (NO2) | 0 ppm | Weekly (daily during cycling) |
| Nitrate (NO3) | Under 20 ppm (under 40 acceptable) | Weekly |
| pH | 6.5-7.5 for most community fish | Weekly |
| Temperature | 76-80F for tropical | Daily (glance at thermometer) |
| GH (general hardness) | 4-12 dGH for most | Monthly |
| KH (carbonate hardness) | 3-8 dKH | Monthly |

### Water Change Protocol
- **Weekly 25-30% water change** is the foundation of aquarium health
- Use a gravel vacuum/siphon to remove debris from substrate while draining
- Replace with temperature-matched, dechlorinated water
- Consistency is more important than volume - weekly is key

### Common Water Issues
- **High ammonia**: Not cycled, overstocked, overfeeding, dead fish/plant
- **High nitrate**: Insufficient water changes, overstocked, overfeeding
- **pH crash**: Low KH (buffering capacity), add crushed coral or baking soda
- **Cloudy water**: Bacterial bloom (new tank, usually resolves in days), green water (algae bloom, reduce light)

## Planted Tank Basics

### Why Live Plants?
- Absorb nitrate (natural filtration)
- Produce oxygen
- Provide hiding spots for fish (reduces stress)
- Compete with algae for nutrients
- Create a natural, beautiful environment

### Easy Beginner Plants (Low Light, Low Tech)
- **Java Fern**: Attach to wood/rock, do NOT bury rhizome, nearly indestructible
- **Anubias**: Attach to hardscape, slow-growing, very hardy
- **Java Moss**: Attach anywhere, great for shrimp, fast spreading
- **Amazon Sword**: Root feeder, needs root tab fertilizer, grows large
- **Cryptocoryne**: Various species, root feeders, may "melt" when first planted (recovers)
- **Hornwort**: Floating or planted, fast-growing, great for beginners
- **Vallisneria**: Grass-like, spreads by runners, easy and attractive

### Planted Tank Requirements
- **Light**: 6-8 hours per day, plant-specific LED (too much light = algae)
- **Substrate**: Nutrient-rich soil (Fluval Stratum, UNS Controsoil) or gravel with root tabs
- **Fertilizer**: Liquid fertilizer (Seachem Flourish, Easy Green) 1-2x per week
- **CO2**: Not required for easy plants. Injected CO2 dramatically improves growth for demanding species.
- **Timer**: Automate lighting schedule for consistency (prevents algae)

## Aquascaping Styles

### Iwagumi
- Japanese rock garden aesthetic
- Odd number of rocks (typically 3-5) arranged with one dominant stone
- Simple carpet plants (Monte Carlo, dwarf hairgrass)
- Minimalist, serene, challenging to maintain (requires CO2 and high light for carpet)

### Nature Style (Takashi Amano)
- Mimics natural landscapes
- Driftwood, rocks, diverse plant species
- Creates depth and perspective
- The most popular and approachable style
- Example: Forest scene with branching wood, mosses, stem plants

### Dutch Style
- Plant-focused, dense, colorful arrangement
- No visible hardscape (wood/rock hidden by plants)
- Uses "streets" (rows of plants creating depth)
- Requires extensive plant knowledge and maintenance
- Like an underwater flower garden

### Jungle Style
- Overgrown, wild, natural appearance
- Low maintenance once established
- Let plants grow freely with minimal trimming
- Dense, provides excellent fish habitat
- Good for beginners who want a planted look without precision

### Hardscape Tips
- Use the rule of thirds for focal point placement
- Odd numbers of rocks look more natural than even
- Create depth: Taller elements in back, shorter in front
- Substrate slope: Higher in back than front creates perspective
- Research rock and wood safety: Some materials alter water chemistry

## Maintenance Schedule

### Daily (2 minutes)
- Check temperature
- Observe fish for unusual behavior, spots, or injuries
- Verify filter and heater are running
- Feed fish (only what they eat in 2-3 minutes, once or twice daily)

### Weekly (30 minutes)
- 25-30% water change with gravel vacuum
- Test water parameters (ammonia, nitrite, nitrate, pH)
- Clean glass (algae scraper or magnetic cleaner)
- Remove dead plant leaves
- Check filter flow (reduced flow may mean it needs cleaning)

### Monthly (30-60 minutes)
- Clean or replace filter media (rinse in old tank water, NEVER tap water - chlorine kills beneficial bacteria)
- Trim plants
- Check equipment (heater thermostat, airline tubing, light timer)
- Clean the outside of the tank and stand

### As Needed
- Replace filter media as it deteriorates (not all at once - keep some established media)
- Replace light bulbs/LEDs (annually or as output diminishes)
- Descale heater
- Replace air stones (every 3-6 months if using air pump)

## Disease Prevention and Treatment

### Prevention (Best Medicine)
- Quarantine new fish for 2-4 weeks before adding to main tank
- Maintain water quality (weekly water changes, do not overstock or overfeed)
- Avoid stress (sudden temperature changes, aggressive tank mates, poor water quality)
- Feed quality food, varied diet
- Do not buy fish from tanks where other fish appear sick

### Common Diseases

**Ich (White Spot Disease)**
- Symptoms: White spots like grains of salt on body and fins
- Treatment: Raise temperature to 86F for 2 weeks, add aquarium salt (1 tbsp/5 gal), or use Ich-X medication
- Highly contagious, treat the whole tank

**Fin Rot**
- Symptoms: Frayed, disintegrating fins, often with reddened edges
- Cause: Bacterial, usually triggered by poor water quality
- Treatment: Improve water quality (frequent changes), antibacterial medication if severe

**Dropsy**
- Symptoms: Bloated body, scales sticking out like a pinecone
- Cause: Internal organ failure, often untreatable
- Treatment: Isolate, Epsom salt bath, antibiotics (low success rate)
- Often a sign of underlying chronic water quality issues

**Velvet**
- Symptoms: Gold/rust dust-like coating, fish rubbing against objects
- Treatment: Dim lights (parasite is photosynthetic), copper medication, raise temperature

### Medication Guidelines
- Always remove activated carbon from filter before medicating (carbon absorbs medication)
- Follow dosing instructions exactly
- Complete the full treatment course
- Quarantine when possible (avoid medicating the whole tank unnecessarily)
- Live plants and invertebrates (snails, shrimp) are sensitive to many medications - research compatibility

## Feeding

### General Guidelines
- Feed only what fish consume in 2-3 minutes
- Once or twice daily (once is fine for most fish)
- Remove uneaten food to prevent water quality issues
- Fast one day per week (optional, mimics natural conditions, aids digestion)

### Food Types
- **Flakes/pellets**: Staple diet, choose quality brands (Hikari, New Life Spectrum, Fluval Bug Bites)
- **Frozen foods**: Bloodworms, brine shrimp, daphnia (excellent supplemental nutrition)
- **Freeze-dried**: Convenient but less nutritious than frozen
- **Vegetables**: Blanched zucchini, cucumber, peas (shelled) for herbivores
- **Algae wafers**: For bottom feeders and algae eaters

## Safety Considerations

- Electrical safety near water: Use GFCI outlet, drip loops on all cords
- Wash hands before and after working in the tank
- Some fish have venomous spines (certain catfish) - handle carefully
- Heavy tanks: Ensure floor and stand can support the weight
- Children should be supervised around aquariums
- Some medications are toxic to humans - wash hands after handling
- CO2 systems operate under pressure - follow manufacturer guidelines

## Progression Path

1. **Phase 1**: Set up 10-20 gallon tank, cycle properly, stock with hardy community fish
2. **Phase 2**: Add live plants (easy species), learn water chemistry, establish maintenance routine
3. **Phase 3**: Upgrade or add a second tank, try aquascaping, explore new species
4. **Phase 4**: Planted tank with CO2, demanding fish species, possible breeding project
5. **Phase 5**: Advanced aquascaping, high-tech planted tank, rare or challenging species
6. **Phase 6**: Competition aquascaping, mentoring beginners, contributing to the community

## Resources

- **Websites**: Aquarium Co-Op (aquariumcoop.com) - educational content and quality products
- **YouTube**: Aquarium Co-Op, Foo the Flowerhorn, MD Fish Tanks, SerpaDesign (aquascaping)
- **Books**: "The Simple Guide to Freshwater Aquariums" by David Boruchowitz
- **Apps**: AqAdvisor (stocking calculator), Aquarimate
- **Forums**: r/Aquariums, r/PlantedTank, The Planted Tank forum
- **Local**: Fish stores (NOT big box pet stores) provide expert advice and healthier fish


## Output Format

Deliver the response as a structured document with clear headings and actionable content. Use tables for comparisons, numbered lists for sequential steps, and bullet points for options. Include specific examples where applicable.

```
[Aquarium Keeper deliverable]
1. Context and objectives
2. Analysis or framework
3. Specific recommendations with rationale
4. Action items with timeline
```


## Example

**Input:** "Help me with aquarium keeper for a mid-size project."

**Output:** A complete aquarium keeper framework tailored to the specific context, with actionable steps, relevant considerations, and measurable outcomes.


## Edge Cases

- **Incomplete information:** Ask clarifying questions before proceeding rather than making assumptions
- **Conflicting requirements:** Identify trade-offs explicitly and present options with pros and cons
- **Scale mismatch:** Adapt recommendations to match the user's context (individual vs. team vs. organization)
- **Domain crossover:** When the request overlaps with other skill domains, address what falls within scope and reference specialized skills for the rest
