Fishkeeping 101 - Community

Yes. Fishkeeping 101 is a beginner fishkeeping course by Cropita Aquatics that walks you through starting a guppy or platy tank, from an empty tank to a healthy one, with short video lessons and 11 printable checklists. It's $9.99/month, and you can cancel anytime.

No. It starts with an empty tank: choosing guppies or platies, picking a tank size and buying the right equipment. No experience needed.

No. Start with Modules 2 and 3 (cycling and water testing) and Module 10 (troubleshooting) to protect the fish you have right now.

Yes. Lessons are short videos that play on any phone, tablet or computer, and the checklists are printable PDFs that are also easy to read on a phone.

Full access for as long as you're subscribed. Cancel anytime.

If the course isn't right for you, email [email protected] within 7 days of your first monthly payment and we'll refund that first payment. Payment processing fees aren't refunded, and course access ends when the refund is issued. You can cancel anytime, and cancelling stops all future charges. Later monthly payments aren't refunded.

No. The disease lessons are general education. Always follow the medication label, and ask an aquatic vet if a problem keeps coming back.

No. The course works wherever you buy your fish.

The course is in English.

Cycling means growing the good bacteria that make a tank safe before fish go in. Fish waste turns into ammonia; bacteria turn ammonia into nitrite, then into nitrate. A new tank doesn't have those bacteria yet, which is why fish added to an uncycled tank often get sick or die.

Fill the tank, add a dechlorinator rated for chlorine and chloramine, and run the filter and heater all day. Dose pure aquarium ammonia (no soap or scent) to about 2 ppm, never above 5 ppm, then test every 2–3 days and log ammonia, nitrite, nitrate and pH. Top the ammonia back up when it gets low.

Usually about 4–8 weeks: RSPCA says around 4–6 weeks, UF/IFAS says a new biofilter needs 6–8 weeks. Seeding with media from a healthy tank can speed it up. Your test kit decides, not the calendar.

Add a full ammonia dose. If ammonia and nitrite both read 0 within about 24 hours and you can see nitrate, the tank is cycled. Then do a big water change to bring nitrate down and add just a few fish at a time.

No. The RSPCA says ammonia is toxic to fish at 0.1 ppm, and many test kits' lowest color step is 0.25 ppm. It's also more toxic in warm, higher-pH water, which is exactly what guppies and platies live in. In an established tank, any reading above 0 needs action: a partial water change, lighter feeding, find the cause, retest the next day.

Ammonia 0 and nitrite 0, always. Nitrate no more than 20 mg/L above your tap water (OATA). pH 7.0–8.0, kept stable. Hardness: guppies 8–18 °dH, platies 4–12 °dH, so about 8–12 °dH if you keep both. Temperature: guppies 20–28°C (68–82°F), platies 17–27°C (63–81°F); the mid-70s °F (about 24°C) suits both.

OATA recommends at least 45 liters (about 12 US gallons) for a small group of either. A common 10-gallon (about 38 L) is a little under that and leaves little margin for error. If you can, go for something in the 15–20 gallon range.

There's no reliable fish-per-gallon formula. Start with a few fish and add more in stages, at least a couple of weeks apart, testing ammonia and nitrite in between. If a normal 25% weekly water change keeps ammonia and nitrite at 0 and nitrate in range, your stocking works. Plan for babies: a mixed tank of 6 fish can be 30 in a few months.

At least 2 females per male (OATA), or 1 male to 2–3 females (Aquarium Co-Op), so females aren't harassed. An all-male tank avoids harassment and babies. Females from a mixed tank are often already pregnant and can store sperm.

About 25% every week (OATA; RSPCA says 10–25%). Test first, unplug the heater before the level drops, vacuum part of the gravel with a siphon (never start it by mouth), and refill with temperature-matched, dechlorinated water. Rinse filter media only in removed tank water, never under the tap, and don't replace all of it at once.

Float the sealed bag to match temperature, then add a small cup of tank water about every 5 minutes for about 20 minutes. Net the fish across and throw the bag water away. Keep lights off and skip food on day one. Quarantine in a separate tank for at least 30 days (the Merck Veterinary Manual minimum), and restart the count after any treatment.

Feed only what they finish in a few minutes. For most adult fish, once a day is plenty (OATA, UF/IFAS); some keepers split it into two small feedings (Aquarium Co-Op). Leftover food rots into ammonia, so if food reaches the bottom and sits, feed less. Begging at the glass is instinct, not hunger.