DIY project

How to build a DIY automatic fish feeder

Advanced (electronics)7 steps$20

What you'll need

Arduino Uno or Nano
Servo motor (SG90 hobby servo)
Battery pack (4xAA)
Plastic feeder cup with sliding door
Mounting bracket
Fishing line
Weatherproof project enclosure

Step-by-step

Step 1: Decide build vs buyHonest reality: Eheim Twin + Petlibro are $25-40 retail. Building a DIY feeder from scratch costs $20-40 in parts + 4-8 hours of work. Most aquarists are better off buying.

Step 2: Build only if you want a programming projectDIY feeder makes sense if: you want a programmable feeder with custom feeding schedules, you have an Arduino + servos lying around, you want to integrate with home automation (Home Assistant, Apex).

Step 3: Mount servo + feeder cupServo motor rotates a sliding door on the feeder cup. Mount the assembly above the tank with a bracket.

Step 4: Wire Arduino + servoServo: signal pin to Arduino digital pin 9. Servo: power to 5V battery. Servo: ground to Arduino ground. Battery to Arduino VIN.

Step 5: Program feeding scheduleUse Arduino IDE: setup() initializes servo. loop() checks RTC time; if feeding time, rotate servo to dispense, wait 2 seconds, rotate back. Feed 2-3x daily.

Step 6: Test and tuneTest dispense over a paper plate first. Verify portion size. Adjust servo angle or rotation duration to control food amount.

Step 7: Mount above tankPosition feeder above tank + bracket secures to stand or wall. Make sure servo + Arduino are protected from humidity (project enclosure).

FAQ

Should I build or buy an auto-feeder?

95% of aquarists should buy. Eheim Twin + Petlibro are $25-40 with proven reliability. DIY only makes sense for programming hobbyists or home-automation integration.

Are auto-feeders accurate?

Reliable brands (Eheim, Petlibro) dose consistent portions. Cheap brands ($10) have variable dispensing + jams = ammonia spike risk.

Can auto-feeders replace a person while on vacation?

For 7-14 day trips: yes. For longer: combine auto-feeder with neighbor check-ins for power + leak alerts.

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Aquarium-keeping fundamentals

Whatever specific topic brought you here, four fundamentals govern long-term aquarium success: water quality, parameter stability, biological filtration, and species-appropriate husbandry. Skip any one and the others struggle to compensate.

Water quality: ammonia + nitrite at zero, nitrate under 30 ppm freshwater + 10 ppm reef. Test weekly with API or Salifert kits. Use our water parameter checker to score your readings against your tank type.

Parameter stability: stable wrong parameters beat fluctuating ideal parameters. Most fish tolerate a wide pH range if it's stable. Sudden swings of 0.4+ pH or 5+°F kill fish faster than chronic suboptimal values. Use temperature controllers (Inkbird) + automated dosing for consistency.

Biological filtration: the bacterial colony on your filter media + rock + substrate is the engine. Never replace all media at once. Use our filter turnover calculator to size correctly.

Species-appropriate husbandry: research adult size, territoriality, diet, and tankmate compatibility before purchase. Use our tank stocking calculator + compatibility guides.

Frequently asked questions

How long does an aquarium take to set up? 4-6 weeks for full cycling + first stocking. Use our cycle ETA calculator + how long does cycling take.

What's the best aquarium for beginners? 20-gallon long. Big enough for parameter stability, small enough for budget + space. See beginner picks.

How often should I do water changes? 25-30% weekly. See water change frequency Q&A + water change calculator.

Why does my fish keep dying? 5 leading causes: uncycled tank, wrong species pairings, no quarantine, undersized tank, neglected water-change schedule. See full diagnosis.