Clear Water is a Lie: The “Invisible Killers” in Your Tank

You just bought a tank. You filled it with tap water. You put the fish in.

Three days later, the water is cloudy, and the fish is dead.

You ask: “What happened? The water looked fine!”

Welcome to New Tank Syndrome.

Your fish didn’t die of hunger or stress. He died because he was swimming in his own toilet.

1. The “Big Three” Toxins (The Nitrogen Cycle)

You don’t need a PhD, you just need to know this chain reaction:

1. Ammonia (The Instant Killer):
   • Source: Fish poop and uneaten food.
   • Effect: It burns the gills. The fish gasps for air.
   • Safe Level: 0 ppm. (Even a tiny bit is toxic).
2. Nitrite (The Suffocator):
   • Source: Bacteria eat Ammonia and turn it into Nitrite.
   • Effect: It stops the blood from carrying oxygen.
   • Safe Level: 0 ppm.
3. Nitrate (The Slow Poison):
   • Source: Good bacteria eat Nitrite and turn it into Nitrate.
   • Effect: Safe in low amounts, but deadly if it builds up over weeks.
   • Safe Level: Below 40 ppm.
   • The Fix: The only way to remove Nitrate is to change the water.

2. The “Tap Water” Enemy (Chlorine)

Tap water is treated with Chlorine to kill bacteria.

Chlorine kills fish. It burns their slime coat instantly.

• The Rule: You MUST use a Water Conditioner (Anti-Chlorine) every single time you add water.
• Recommendation: Seachem Prime (The best) or any generic “Anti-Chlorine” from the LFS (Local Fish Shop). Never skip this.

3. The “Clean Freak” Mistake

This is where most beginners fail.

They see dirty gravel, so they take the whole tank to the bathroom, dump all the water, scrub the gravel, and wash the filter sponge with soap.

STOP. You just nuked your tank.

• Beneficial Bacteria: Good bacteria live in your filter sponge and gravel. They eat the Ammonia.
• The Rule: Never wash your filter media in tap water. Rinse it gently in old tank water during a water change. If you kill the bacteria, the cycle restarts, and your fish dies.

4. The Maintenance Schedule (The Lazy Way)

You don’t need to change 100% of the water (unless the tank is tiny and uncycled). That shocks the fish.

Do this instead:

• Frequency: Once a week (e.g., Sunday).
• Amount: Change 20% to 30% of the water.
• Tool: Use a Siphon (Gravel Vacuum). Don’t just scoop water from the top. The poop is at the bottom. Suck the dirt out of the gravel.

5. The “Malaysia” Factor (Temperature)

Most online guides scream: “You need a heater!”

• In the West: Yes, they have winter.
• In Malaysia: Our water is naturally 27°C – 29°C. This is perfect for Bettas.
• The Exception: If you keep your fish in an Air-Conditioned room (20°C – 24°C), you DO need a heater. Cold water causes constipation and Ich.

Summary: The “Perfect Water” Checklist

The Shop Guy’s Verdict

Fish keeping is actually “Water Keeping.”

If you keep the water good, the fish takes care of itself.

Buy a Liquid Test Kit (like API Master Kit). It costs RM100+, but it saves you RM500 in dead fish.