Prophylactic Treatment New Fish Protocol: Praziquantel, Metroplex, Copper

Waiting for a fish to show symptoms before treating is a losing strategy in marine quarantine. Flukes can be invisible for weeks, internal parasites rarely announce themselves, and ich often hides in the gills before surfacing on skin. A structured prophylactic treatment new fish protocol cycles praziquantel, metroplex, and copper in sequence so every incoming fish leaves quarantine clean regardless of what it arrived carrying. This guide from Gensou Aquascaping in Singapore covers the order, doses, and overlap rules that keep the protocol from stressing the fish more than the disease would.

Quick Facts

• Total quarantine length: 30 days minimum across three treatment phases
• Praziquantel (PraziPro): 5 ppm, two doses 5-7 days apart for flukes and tapeworms
• Metroplex: 250 mg per 40 litres, with food for internal parasites, 14 days
• Copper (Cupramine): 0.35-0.5 ppm over 14-21 days for ich and velvet
• Never run copper alongside prazi in the same 48-hour window — too stressful
• Observation-only final week to confirm appetite and behaviour before display
• Use a separate bare-bottom tank; copper binds to rock, sand, and ceramics

Why Prophylactic Treatment Makes Sense

Most marine livestock in Singapore comes through transshipment with stress, fasting, and crowded bags. Even tank-bred clownfish from reputable local farms can arrive with low-level parasite loads that explode when added to a reef. Treating every new fish preventively — rather than reactively — stops the display from becoming a long-running infirmary.

The protocol uses three medications because no single treatment covers every common pathogen. Copper addresses the two worst killers (ich and velvet), prazi handles flukes, and metroplex targets internal flagellates and bacterial issues.

Phase One: Praziquantel

Start with prazi on day 1-7. Dose PraziPro at 5 ppm (2.5 ml per 40 litres for the standard 1% concentration), leave in the water for 5-7 days, then do a 50% water change and run carbon for 24 hours to strip the medication. Prazi is gentle and lets you observe the fish during early acclimation without the aggression of copper.

Repeat a second prazi dose on day 14-20 during the observation gap after copper, to catch any fluke eggs that hatched after the first round.

Phase Two: Copper Treatment

Between days 8 and 22, ramp Cupramine to 0.35 ppm over 48 hours, then hold 0.5 ppm for 14 days confirmed by a Hanna or Salifert copper test kit. Daily checks matter because copper drops as it binds to any organic. Re-dose to bring the level back each morning.

Do not use copper on sharks, rays, mandarins, scooter blennies, or pufferfish — for those species, substitute chloroquine phosphate or tank transfer method. Angelfish, particularly Centropyge, tolerate copper but watch closely for appetite loss.

Phase Three: Metroplex Food Soak

From day 16-29, soak pellets or mysis in a metroplex and focus mixture (250 mg metroplex plus 2.5 ml focus per tablespoon of food) and feed twice daily. This treats internal flagellates such as Uronema and early hexamita before they cause weight loss. Food-borne dosing is more effective than water dosing because metroplex is absorbed orally.

Continue regular feeding alongside the medicated portion. Fish that refuse medicated food during copper treatment often eat it again once copper is removed.

Overlap Rules and Safe Sequencing

Never combine prazi and copper in the same 48 hours. The double oxidative stress drops appetite and can trigger secondary bacterial infections. Metroplex in food is compatible with either water treatment because it bypasses the water column. Leave at least 24 hours of carbon filtration between medication phases to clear residuals.

Observation and Final Clearance

Days 23-30 are medication-free observation. Watch for flashing, rapid breathing, or clamped fins. Appetite should be strong, colour even, and behaviour active. Any symptom restarts the clock on that specific phase — a fish showing ich spots on day 28 goes back on copper.

A final freshwater dip (pH and temperature matched, 4-5 minutes) immediately before adding to the display provides a last kill for any missed flukes.

Tank Setup for the Protocol

Bare-bottom 40-80 litre tank, sponge filter seeded from a healthy system, heater to 26°C, PVC elbows for hiding. Do not add sand or rock. Copper absorbs into anything porous and leaches back for years. A simple setup in Singapore runs $100-180 from C328 or the Pasir Ris farms, and pays for itself the first time it stops a reef-wide outbreak.

Related Reading

How to Quarantine Marine Fish Complete
How to Set Up Marine Quarantine Tank
Aquarium Praziquantel Dosing Guide
Marine Ich Cryptocaryon Treatment
Best Aquarium Copper Test Kit