Guide 37 — Care Guide

Temperature, Heating & Thermal Shock

Temperature is easy to overlook because it's easy to measure and easy to assume is fine. This guide covers safe ranges for snails and shrimp, why the rate of change matters more than the number itself, and how to acclimate to temperature safely.

Typical Safe Ranges

Most of the snail and shrimp species commonly kept in home aquaria — Neocaridina shrimp and species such as Malaysian Trumpet Snails, Ramshorns and Bladder Snails — tolerate a fairly wide range, broadly around 18-28°C (64-82°F), with a narrower comfortable band typically cited around 20-25°C (68-77°F) where metabolism, feeding, moulting and breeding all proceed steadily rather than being pushed to either extreme.

Species do vary, and Caridina-type shrimp in particular tend to be less tolerant of the upper end of that range than Neocaridina. Always check the specific tolerance of what you're keeping rather than assuming every snail or shrimp species shares identical requirements — this guide describes general principles that apply broadly, not a single number that fits every species without exception.

Why the Rate of Change Matters

Thermal shock isn't really about a specific temperature being dangerous — it's about how quickly the change happens. A shift of a couple of degrees over several hours is generally well tolerated; the same shift happening within minutes is a genuine stressor and, in a sudden or large swing, can be fatal. As a working guideline, keep changes to no more than around 1-1.5°C per hour, and ideally slower than that for anything beyond a small adjustment.

This is why room temperature fluctuation matters more for an unheated tank than many keepers expect — a cold snap or a heatwave affecting room temperature over a day or two is a gradual, generally tolerable change, but something like moving a tank near a draughty window or a radiator that cycles sharply on and off can create faster swings than are obvious just from checking a thermometer once a day.

Acclimating New Arrivals to Temperature

New livestock arriving in a transport bag or container is one of the most common points where a sudden temperature change can happen if it isn't managed deliberately. Floating a sealed bag in the destination tank for around 15-20 minutes allows the water inside to gradually match tank temperature before any mixing of water happens, and is a standard first step regardless of what's being acclimated.

For shrimp specifically, it's worth pairing this with the slower drip or gradual water-mixing acclimation already covered for water chemistry, since temperature and water parameter changes are often happening together during acclimation and shrimp are sensitive to both. Snails generally tolerate a faster process than shrimp, but the same floating step still applies.

Heaters and Where They Go Wrong

Many UK homes run a stable enough room temperature that a heater isn't strictly necessary for most snail and shrimp species year-round, particularly with central heating in winter. Where a heater is used, the most common failure mode isn't the heater failing to switch on — it's a stuck heater failing to switch off, which can push a tank well outside a safe range before anyone notices. A separate thermometer positioned away from the heater itself, checked as part of a normal routine, is the simplest way to catch this early rather than trusting the heater's own indicator light alone.