Ooo, this is something I was thinking of doing too. Great idea.
I found a guide on how to acclimatise house plants for hydroponics, which is pretty much the same thing as you're doing. They also recommended a list of plants that can be kept this way. Note that some plants from the list might be poisonous if eaten (fish might graze on the roots I imagine).
The guide recommended that the plant is covered in plastic for 2-3 weeks after being put in the water to prevent excess water evaporation.
Here's the list of recommended plants:
Abutilon, Achimenes, Adenium, Aeschynantus speciosus, Afelandra squarrosa, Anturium x scherzerianum, Ardisia crenata, Argyranthemum, Callistephus chinesis, Rhododendron simsii, Catharanthus roseus, Begonia, Begonia scharffii, Browallia speciosa, Brunfelsia pauciflora, Bougainvillea glabra, Zantedeskia, Celosia argentea, Cyklamen persicum, Senecio cruentus - mieszańce, Mimosa, Campanula isophylla, Aechmea fasciata, Echeveria, Euryops chrysanthemoides, Eustoma grandiflorum, Exacum affine, Freesia, Gardenia jasminoides, Gerbera, Gloriosa rothschildana, Gmphrena, Hyacinthus orientalis, Hippeastrum vittatum, Hoya, Hydrangea macrophylla, Ixora coccinea, Iris reticulata, Justica carnea, Jasminum, Kalanchoe blossfeldiana, Kalanchoe pumila, Kalanchoe 'tessa', Calceolaria x herbeohybrida, Camelia japonica, Anigozanthos flavidus, Hibiskus rosa-sinensis, Clivia miniata, Crocus, Selenicereus grandiflorus, Curcuma, Leptospermum scoparium, Lilium longiflorum, Catharanthus roseus, Mammilaria zeilmanniana, Medinilla, Passiflora, Citrus mitis, Hypocyrta glabra, Narcissus, Nertera, Impatiens, Orbea variegata, Calathea crocata, Pelargonium grandiflorum, Peperomia caperata, Pentas lanceolata, Primula obconica, Solanum pseudocapiscum, Capsicum annuum, Puschkimia scilloides, Rehmania elata, Rosa, Saintpaulia, Sreptocarpus, Spathiphyllum, Smithiantha, Senecio grandifolius, Stephanotis floribunda, Cymbidium, Dendrobium, Odontoglossum, Cattleya, Miltonopsis, Phalenopsis, Phragmipedium, Pleione bulbocodioides, Paphiopedinum insigne, X vuylstekeara, Strelitzia reginae, Justicia brandegeeana, Syningia, Muscari armeniacum, Oxalis, Tulipa, Euphorbia milli, Euphorbia pulcherrima, Ipomoea, Dendrathema grandiflorum, Lithops.