# Why Does FCR Rise in Fish? 8 Common Causes

> Overfeeding, temperature, low oxygen, stocking density, disease, feed quality, measurement error and stress: the 8 most common causes of rising FCR and how to fix them.

- URL: https://demo.fcrsoft.com/en/fcr/why-does-fcr-increase
- Language: en
- Updated: 2026-10-03
- Publisher: FCRSOFT (https://fcrsoft.com)

[Demos](https://demo.fcrsoft.com/?hl=en) / [Knowledge Center](https://demo.fcrsoft.com/en/guides) / Why Does FCR Rise in Fish? Guide

# Why Does FCR Rise in Fish?

A rising FCR shows that feed is not turning into growth. There is rarely a single cause; checking the eight points below in order makes the problem easier to find.
[See the system that does this automatically Open the live demo](https://demo.fcrsoft.com/login.php?package=farm)

## Overfeeding and feed loss

Feed given beyond appetite sinks or is carried away by the current; it adds to FCR without turning into growth.

## Unsuitable water temperature

Outside the species’ suitable range, metabolism and digestion slow down; the same amount of feed gives less growth.

## Low dissolved oxygen

When oxygen drops, fish cannot fully use the feed and lose appetite; early mornings are especially risky.

## High stocking density and size differences

Crowding and size differences increase competition; big fish take the feed while the small ones fall behind.

**Track Your FCR Automatically**Instead of doing this by hand every month, let FCRSOFT calculate your FCR per cage automatically with every feeding and weighing record.
[Open the live demo](https://demo.fcrsoft.com/login.php?package=farm) [Fish Farm Management Software](https://demo.fcrsoft.com/en/solutions/fish-farm-management-software)

## Disease and parasites

Sick fish eat less and spend their energy on immunity; deaths also raise economic FCR.

## Feed quality and storage

Feed that is stored badly or gets old loses nutritional value; if the pellet size does not match the fish size, feed is wasted.

## Inaccurate biomass estimate

If sample weighing is inadequate, biomass looks higher or lower than it really is and FCR is calculated wrongly.

## Stress

Stressors such as transport, net changes, grading and noise lower appetite for several days.

[Free tool Why Is Your FCR Rising?](https://demo.fcrsoft.com/en/tools/why-is-my-fcr-high-test) FCRSOFT

## FCRSOFT does this for you automatically

You don’t need to do the calculations and checks on this page by hand every day. FCRSOFT derives them all automatically from the records entered in the field.

- FCR and biomass are updated per cage with every feeding and weighing record.

- FCR values above target are flagged in the panel.

- Economic and biological FCR reports are ready by batch and period.

[Open the live demo](https://demo.fcrsoft.com/login.php?package=farm) [Explore the Farm package](https://demo.fcrsoft.com/demo/farm?hl=en)

[demo.fcrsoft.com](https://demo.fcrsoft.com/login.php?package=farm)

Last updated: 10/3/2026

## Related tools and guides

[Free tool ### Why Is Your FCR Rising? Find the likely cause of a rising FCR with nine short questions: feeding, water quality, stocking density, health, feed quality or measurement error. Open the tool](https://demo.fcrsoft.com/en/tools/why-is-my-fcr-high-test) [Guide ### How to Improve FCR Ways to lower FCR with feeding tables, temperature-based feeding, appetite monitoring, the right pellet size, grading, oxygen management, feed storage and data-driven tracking. Read the guide](https://demo.fcrsoft.com/en/fcr/how-to-improve-fcr) [Free tool ### Water Quality Checker Choose your species and enter temperature, dissolved oxygen, pH, ammonia, nitrite and salinity to see a good, caution or critical status for each parameter. Open the tool](https://demo.fcrsoft.com/en/tools/water-quality-checker) [Free tool ### FCR Calculator Free FCR calculator: instantly work out economic and biological FCR, feed cost per kg and the savings from a 0.1 FCR improvement, from biomass gain and feed given. Open the tool](https://demo.fcrsoft.com/en/tools/fcr-calculator)