Most research into the welfare and behaviour of ornamental fish species has focusedon conditions within the ornamental trade itself, with welfare once fishes reach theirend destination of home aquaria often overlooked. Additionally, there is littledocumented evidence on common husbandry practices carried out by hobbyistsacross the UK, including the use of enrichment in aquaria. A variety of enrichmenttypes are available to the home aquarist including physical enrichment (e.g., plants,substrate), dietary enrichment and sensory enrichment (e.g. lighting) but there hasbeen only a small amount of research into the effects of adding enrichment to homeaquaria. While some enrichment may be beneficial through increased environmentalcomplexity stimulating the expression of natural behaviours, the addition of sometypes of physical structures, in particular substrate, can increase the growth ofpotentially harmful bacteria. This thesis firstly reviewed current literature on fishwelfare, focusing particularly on the ornamental trade and the use of environmentalenrichment. The experimental component of the thesis comprised a lab study, whichused simulated home aquaria to record fish behaviour in relation to four differentsubstrate types. Simulated home aquaria containing a benthic (Corydoras sp.) andopen water (zebrafish; Danio rerio) fish species were maintained for 10 weeks duringwhich time behavioural recordings were carried out to understand the influence ofsubstrate on fish behaviour. To further understand hobbyist practices in the UK, asurvey of UK home aquarium owners was carried out to understand the mostpopular fish species kept, the use of different enrichment types and how fishes arecared for. In the experimental study, the type of substrate, including colour, wasfound to affect fish behaviour particularly following the addition of food. More effectswere seen in the benthic Corydoras compared to zebrafish. The UK survey workindicated that the majority of participants used substrate in their home aquaria,although the most prominent reason given for use of substrate was aesthetic ratherthan being welfare-orientated. In conclusion, the welfare of fishes within homeaquaria is still understudied, particularly when compared with research into thewelfare of other companion animals. Given the prevalence of substrate use in homeaquaria throughout the UK and its potential benefits for fish behaviour, there is aneed to further understand the negative aspects of this enrichment type through thegrowth of harmful bacteria, which can cause disease and illness in both fishes andhumans.