Welfare considerations for fasting fish.

This is an interesting read. I often get questioned by fish owners about how long can you go on holidays without getting someone in to feed your fish. It’s a very good question and is difficult to answer. The greatest issue with getting someone in to feed your fish is that very often, they are overfed. The uneaten food will pollute the water and you get mass mortalities. This would be a disaster!

On the other hand, if you don’t get someone in to feed your fish, how long can you do this for? This experiment shows that, in rainbow trout at least, there are no welfare issues with fasting for up to 3 days (58.0°C days).

Aquaculture
Volume 401, Number 24 (June 2013)
	Short-term fasting and welfare prior to slaughter in rainbow trout, Oncorhynchus mykiss
	Authors:	J. López-Luna, L. Vásquez, F. Torrent, M. Villarroel
	Author Affiliations:	no affiliations available
	Source:	Aquaculture, Volume 401, Number 24 (June 2013)
	Page Numbers:	142 – 147
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	Abstract:	Fasting fish before slaughter is a common practice in aquaculture but it is not clear how long rainbow trout can be starved before suffering unnecessary stress, nor at what moment of the day slaughter is least stressful. We fasted 90 rainbow trout (Oncorhynchus mykiss; initial average weight 215.0±22.6g) for 24, 48 and 72h (19.5, 38.8 and 58.0°Cdays) and slaughtered them in the morning (08h00), afternoon (14h00) and night (20h00) to observe the effect of fasting duration and slaughter time on welfare indicators, including plasma cortisol, glucose and lactate concentrations as well as hematocrit and leucocyte count. The values of the fasted fish were compared with 90 control fish kept under similar conditions but not fasted. Body weight was not significantly different between fasted fish and controls during the trial but the relative weight of the gut was higher in control trout. Cortisol levels were similar between fasted and control fish and among the treatment groups. Similar results were found for glucose and lactate concentrations in plasma. Hematocrit values were also normal and similar between fasted fish and controls throughout the experiment, but leucocyte count was slightly lower in fasted fish by day three. There were no clear differences in any of the stress parameters in the morning, afternoon and night in either treatment. These results suggest that rainbow trout can cope with fasting up to three days (58.0°Cdays) prior to slaughter and that their welfare is therefore not seriously compromised.
	Citation:	J. López-Luna, L. Vásquez, F. Torrent, M. Villarroel . Short-term fasting and welfare prior to slaughter in rainbow trout, Oncorhynchus mykiss. Aquaculture, Volume 401, Number 24 (June 2013), pp. 142-147, <http://ejournals.ebsco.com/direct.asp?ArticleID=43908152186A7DB49505&gt;
	URL:	http://ejournals.ebsco.com/direct.asp?ArticleID=43908152186A7DB49505