Why you never ever, ever, ever use a fish to cycle...

[Sk8r]

1. it's very cruel. A piece of dead shrimp or a few flakes of fish food daily will do the job just as well. Ammonia either kills or does lifelong organ damage to a live fish, to NO better result. If a fish store tries to tell you otherwise, regard advice from that store as stuck somewhere in the 1960's.
2. if that fish should have a parasite like ich, which lives in infested fish and tank sandbeds, you may just have imported a parasite which may survive to cause you trouble. Set up to quarantine your first single fish for a number of weeks in a small tank with clean saltwater and no rock or sand.

 

[Michael Hoaster]

A recent post here on RC recounted how a new hobbyist added 3 dead shrimp and weeks later, no ammonia spike. One way to guarantee you start with enough ammonia to start a cycle is to USE AMMONIA - right from the grocery store. Here's the basics:

Using Pure Ammonia to Cycle the Aquarium

After the tank has been set up, add five drops of ammonia per ten gallons into the water on a daily basis. Ammonia will rise to five ppm and higher. As soon as nitrites are measurable, reduce the ammonia input to three drops per day. Once Nitrite drops and Nitrate starts rising, you're done!

 

[Sk8r]

And be very, very sure you use pure ammonia.

 

[pmaloy]

Or this is what I use - powdered ammonium chloride:
https://smile.amazon.com/gp/product/B00OTH5TAQ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

 

[cwschoon]

1. it's very cruel. A piece of dead shrimp or a few flakes of fish food daily will do the job just as well. Ammonia either kills or does lifelong organ damage to a live fish, to NO better result. If a fish store tries to tell you otherwise, regard advice from that store as stuck somewhere in the 1960's.
2. if that fish should have a parasite like ich, which lives in infested fish and tank sandbeds, you may just have imported a parasite which may survive to cause you trouble. Set up to quarantine your first single fish for a number of weeks in a small tank with clean saltwater and no rock or sand.

Can you expand upon this please? I am trying to explain to someone, why cycling with fish is wrong, unnecessary and that ANY level of ammonia is harmful to fish. Thanks.

 

[Uncle99]

Fish produce ammonia which moves the cycle “forward”.
Anything breathing produces ammonia.
Initially, there may not be an adequate population to convert ammonia in the water column and this suffocates fish, burning gills. That be cruel.

However, the good news is today, with bottled bacteria easily available, a system, with rock and sand, can be ready for fish within days, or, with live rock, immediately, gone are months of waiting.

Saltwater, Rock, Sand (if you want) a bottle of bacteria, flow…..done…..add one or two, wait a month…..add…
Ok to mix brands, and after the initial dose, small daily doses until bottle gone.