Introduction
Axolotls are one of the most extraordinary creatures you can keep as a pet — part fish, part salamander, all alien charm, with those feathery gills that trail behind them like something from another planet. They’re also notoriously easy to kill if you don’t know what you’re doing.
They’ve been popularised by viral TikTok videos and Minecraft aesthetics that make them look like easy, low-maintenance pets. They’re neither. Axolotls have some of the most specific water quality, temperature, and specific requirements of any amphibian in the trade — and the number of owners who learn this the hard way is quietly alarming.
Here are the 10 mistakes I see most often. Some of them will surprise you.
Mistake #1: Keeping Your Axolotl in a Tank That’s Too Small
This is the single most common axolotl care mistake, and it kills axolotls faster than almost anything else.
The mistake: A goldfish bowl, a 5-gallon tank, or anything under 20 gallons for a single adult axolotl.
Why it’s a problem: Axolotls are surprisingly active for aquatic animals. They pace, they explore, they occasionally do something that looks concerningly like a panic sprint across the tank floor. A cramped tank means ammonia and nitrites build up faster than your filter can handle. Water parameters that are merely marginal in a 20-gallon tank become lethal in a 5-gallon tank within days.
The fix: A minimum of 20 gallons for one adult axolotl, with an additional 10 gallons for every additional axolotl. A 40-gallon breeder tank is ideal. Floor space matters more than height — axolotls walk more than they swim.
Mistake #2: Water That’s Too Warm
Axolotls are cold-water amphibians. This cannot be overstated — and getting this wrong is one of the most common axolotl care errors new owners make.
The mistake: Keeping them at room temperature (72–78°F / 22–26°C) because you didn’t know they needed cool water — or because your room gets warm in summer.
Why it’s a problem: Axolotls evolved in the cool, deep waters of Lake Xochimilco in Mexico, where water temperatures rarely exceed 68°F (20°C). At temperatures above 74°F (23°C), axolotls go into severe heat stress. Their immune systems begin to fail and fungal infections can explode across their body. At 80°F (27°C) and above, prolonged exposure can become fatal — and in severe cases, death can come within hours. Either way, the process is prolonged and deeply damaging.
The fix: Keep your tank water between 60–68°F (16–20°C) year-round. In most climates this means you’ll need a chiller — essentially a small aquarium refrigerator that runs continuously. Aquarium fans can help lower temperature by a degree or two in cooler rooms, but they are not sufficient on their own in warm climates. Budget $150–$300 for a quality aquarium chiller — it is not optional in most setups.
Mistake #3: Using Tap Water Without Dechlorinator
This one catches even experienced fish keepers who assume axolotls are as tough as goldfish. Getting water right is fundamental to proper axolotl care.
The mistake: Filling the tank with straight tap water and assuming it’s safe because it looks clear.
Why it’s a problem: Tap water contains chlorine and chloramine — compounds added at water treatment plants to kill bacteria. These are harmless to humans in trace amounts. They are profoundly toxic to axolotls, damaging their gills, skin, and immune system over time. Even trace amounts that don’t immediately kill your axolotl will cause chronic stress that manifests as gill curling, pale colour, and susceptibility to fungal and bacterial infections.
The fix: Always treat tap water with a quality dechlorinator (Seachem Prime is the most widely trusted in the amphibian keeping community) every time you add new water. Add it during every water change, without exception.
Mistake #4: Too Much Water Movement and Current
Unlike tropical fish, axolotls do not need highly oxygenated, fast-moving water — and this is a critical part of axolotl tank setup that many owners overlook.
The mistake: Adding a powerful air pump, bubble stone, or high-flow filter to maximise oxygen, thinking more circulation is better for your axolotl’s health.
Why it’s a problem: Axolotls come from still, slow-moving waters. They have delicate, feathery external gills that are designed for gentle oxygen exchange in calm water. A strong current from a powerful filter or air pump will pummel their gills, causing them to curl, erode, and become inflamed. Stressed gills are a primary entry point for bacterial and fungal infections. An axolotl in a strong current is an axolotl in constant, exhausting stress.
The fix: Use a gentle sponge filter or a low-flow canister filter rated for the tank size. If your filter creates visible current, redirect the flow with a spray bar or baffle. Your axolotl should be able to rest comfortably in one spot without being pushed around.
Mistake #5: Handling With Bare Hands
This is one that shocks people every time it comes up — and it’s one of the most universally agreed-upon rules in proper axolotl care.
The mistake: Picking up your axolotl with bare hands to move it, show it to someone, or clean its tank.
Why it’s a problem: Axolotls have a slime coat — a protective mucous layer covering their entire body — that functions as their primary defence against bacterial and fungal infection. Human hands are dry, slightly abrasive, and coated in oils, lotions, soaps, and other compounds that strip and damage this slime coat on contact. Every time you pick up an axolotl with bare hands, you remove a layer of its immune defence.
Additionally, axolotls have very fragile bodies. Their internal organs can be damaged by rough handling or impact against tank decor — and they will thrash when stressed, which can cause them to injure themselves on hard surfaces.
In an emergency (such as a water quality crash requiring immediate transfer), a brief transfer using wet hands or a small container is acceptable. Routine handling, however, should be avoided entirely.
The fix: If you must move your axolotl, use a soft, wet mesh net — never a hard plastic net, which can snag and tear gills. Treat handling as a last resort, not a routine activity.
Mistake #6: Adding Tank Mates
This is perhaps the most frequently violated rule in casual axolotl keeping — and one of the clearest signs of inadequate axolotl habitat setup.
The mistake: “I’ll put a few feeder fish in with it to keep it company” or “Can I keep it with my goldfish?” or “Will a turtle work?”
Why it’s a problem: Almost every common aquarium animal is incompatible with axolotls in one of several fatal ways:
- Fin-nipping fish (tiger barbs, bettas, some corydoras) will damage axolotl gills and tails, causing injuries that regularly become infected
- Warm-water fish (most tropical species) need temperatures that will kill axolotls
- Small fish (feeder guppies, goldfish) will attempt to nibble on axolotl gills — and goldfish in particular carry a significant parasitic load, including the tapeworm Bothriocephalus acheilognathi, that transfers easily to axolotls and is frequently fatal
- Crayfish and crabs will actively attack and limb-amputate axolotls
- Other axolotls will sometimes bite each other’s gills, especially in close quarters or when hungry
The fix: Axolotls are solitary animals. One axolotl per tank is the gold standard. If you must keep multiple, you need a very large tank (60 gallons or more), multiple hiding spots, and careful monitoring. Separate immediately at the first sign of nipped gills.
Mistake #7: Gravel or Small Substrate
This is the silent killer that owners don’t notice until the axolotl is critically ill — and it directly contradicts the substrate choices many new owners instinctively make when setting up their axolotl tank.
The mistake: Using small aquarium gravel, sand that is too fine, or any substrate with particles small enough to fit in the axolotl’s mouth.
Why it’s a problem: Axolotls suction-feed. They drop down to the substrate, open their mouths wide, and create a powerful vacuum that pulls food (and surrounding material) in. If the particles on your tank floor are small enough to fit in their mouth, they will accidentally ingest them. Gravel and small stones cause impaction — a blockage in the digestive tract that prevents the axolotl from eating and, if untreated, becomes fatal. The symptoms develop slowly: reduced appetite, bloating, a visibly swollen belly, and constipation that becomes critical over time.
The fix: Use large river stones (smooth, round stones too big to fit in the axolotl’s mouth — generally anything over the size of the axolotl’s eye), or a bare-bottom tank with hiding spots placed on the flat tank floor. Many experienced axolotl keepers prefer bare-bottom setups specifically to eliminate this risk entirely.
Mistake #8: Inconsistent Water Parameters and Maintenance
Axolotls are far more sensitive to water chemistry than most first-time owners realise — and this is the single most important element of long-term axolotl care that people underestimate.
The mistake: Changing the filter media when it gets dirty, doing huge water changes every few weeks, and not testing water parameters at all.
Why it’s a problem: The nitrogen cycle is the foundation of aquarium health. Ammonia (from axolotl waste) converts to nitrite, which converts to nitrate. Ammonia and nitrite are both toxic at any detectable level. If you clean your filter media with tap water, you kill the beneficial bacteria that process ammonia — and your axolotl is suddenly swimming in its own toxic waste.
The fix:
- Never clean filter media in tap water — swish it in old tank water or dechlorinated water only
- Test water parameters with a liquid test kit (API Freshwater Master Test Kit is the standard) every 3–4 days
- Do water changes of 20–30% weekly, not sporadic large changes
- Keep ammonia and nitrite at zero at all times
- Keep nitrates below 20–40 ppm
Mistake #9: Bright Lighting and No Hiding Spots
Axolotls are essentially nocturnal and have no eyelids. Light is a stress factor in ways most owners don’t anticipate — and this is an aspect of axolotl habitat setup that is almost universally overlooked.
The mistake: Placing the tank near a sunny window or under bright aquarium LED lighting, with no caves, plants, or dark spaces for the axolotl to retreat to.
Why it’s a problem: Axolotls have no iris muscles and cannot close their eyes. Bright, direct light — whether from a window or an LED strip — means they are effectively being stared at constantly. This is profoundly stressful. A stressed axolotl will hide constantly, reduce its activity and appetite, and show it through gill curling, pale discolouration, and attempts to burrow under anything in the tank.
Beyond lighting, axolotls are prey animals. They instinctually need a place to retreat where they feel concealed. A tank with nothing in it — no plants, no hides, no decor — is a tank that causes chronic, low-level stress that compounds over months into illness.
The fix: Keep the tank away from direct sunlight. Use low-level ambient lighting on a timer (4–6 hours maximum per day). Provide at least 2–3 hiding spots — PVC pipe bends work perfectly, as do terra cotta pots laid on their side, or purpose-built aquarium hides. Live or soft artificial plants add additional cover and visual complexity.
Mistake #10: Feeding the Wrong Diet — or the Right Diet Wrong
This one trips up almost every first-time axolotl owner — and getting it right is fundamental to long-term axolotl health and longevity.
The mistake: Feeding standard aquarium flakes or pellets, feeder goldfish, or adult axolotls exclusively on bloodworms.
Why it’s a problem: Axolotls are carnivorous ambush predators with very specific dietary needs, and feeding them the wrong things — or the right things in the wrong way — is one of the most common axolotl feeding mistakes in the hobby.
- Aquarium flakes and pellets dissolve in water and foul the tank, and most axolotls won’t recognise them as food
- Feeder goldfish carry parasites (specifically the tapeworm Bothriocephalus acheilognathi, which is well-documented as one of the most common and dangerous pathogens in axolotls) — this risk is real, documented, and frequently fatal
- Bloodworms alone are an excellent treat and good for juveniles, but they lack some nutrients needed for long-term adult maintenance
The fix — by age:
Juveniles (under 3 inches): Night crawlers/earthworms cut into small pieces, or blackworms exclusively
Adults: Night crawlers (earthworms) are the gold standard — nutritionally complete, eagerly accepted, and widely available at any fishing tackle shop. Soft salmon pellets are an acceptable supplement. Feed adults once or twice a week — overfeeding is a real risk, especially in captivity where activity levels are low.
Earthworms from your garden are fine only if you are certain they have not been exposed to pesticides or fertilisers.
Quick Reference: Axolotl Care Mistakes at a Glance
| Mistake | The Quick Fix |
|---|---|
| Tank too small | Minimum 20 gallons; floor space over height |
| Water too warm | Keep at 60–68°F; invest in a chiller |
| Tap water untreated | Seachem Prime every water change, every time |
| Too much current | Low-flow sponge filter; baffle any strong flow |
| Handling bare hands | Wet soft mesh net only; minimise all handling |
| Tank mates | One axolotl per tank. No exceptions |
| Small substrate | Large smooth stones or bare-bottom only |
| Poor water maintenance | Test every 3–4 days; weekly 20–30% water changes |
| Bright lighting | Low ambient light, 4–6 hrs/day; add hides |
| Wrong diet | Earthworms for adults; blackworms for juveniles |