Marine ornamental fish are a key component of the multimillion‐dollar marine aquarium trade industry, a controversial industry due to current heavy reliance on wild‐collected specimens. Aquaculture ...of marine ornamental fish is considered as a sustainable alternative, but it is still in the early stage of development. This review focuses on the current state of marine ornamental fish aquaculture, by covering topics on reef fish reproductive biology in captivity, traditional and novel live feeds, feeding regimes and visual environment in larviculture. Where possible, major differences between demersal and pelagic spawners are compared and discussed. Overall, for many ornamental fish species, natural spawning can be achieved in a captive environment without the use of hormone induction; however, sex identification and successful pairing for reef fish species could be a challenge. With the use of both traditional (rotifers and Artemia) and novel live feeds (e.g. marine copepods and ciliates), a range of breakthroughs in larval rearing of both demersal and pelagic spawning ornamental fish species have been achieved in recent years, although larval survival varies. To further improve the larval rearing success of marine ornamental fish, this review suggests that future research should focus on optimizing the use of live feed in terms of both quality and quantity, and establishment of well‐defined species‐specific larval feeding regime, as well as providing appropriate rearing condition through improved manipulation of light conditions and the ‘greenwater’ techniques in larval rearing.
Ciliates are considered the most harmful parasites of fish, causing mass mortalities and thus substantial economic losses to the aquaculture and ornamental fish industries. To better elucidate their ...pathogenic mechanisms and facilitate the development of effective prevention and control strategies, it is essential to apply novel technologies to ensure the continuous and sufficient supply of parasite specimens. This review discusses the latest research progress in the artificial culture of six important parasitic ciliates affecting both freshwater and marine fish globally: Ichthyophthirius multifiliis, Cryptocaryon irritans, Chilodonella (C. hexasticha, C. piscicolaand C. uncinata), Balantidium ctenopharyngodoni, Scuticociliatida gen. spp., and Tetrahymena spp. Methods for in vitro and in vivo culture as well as cryopreservation/preservation (depending on the specific species) of these organisms are described herein. Challenges and future applications of parasite culture are also discussed.
Antimicrobial resistance (AMR) is a growing threat to human and animal health. However, in aquatic animals-the fastest growing food animal sector globally-AMR trends are seldom documented, ...particularly in Asia, which contributes two-thirds of global food fish production. Here, we present a systematic review and meta-analysis of 749 point prevalence surveys reporting antibiotic-resistant bacteria from aquatic food animals in Asia, extracted from 343 articles published in 2000-2019. We find concerning levels of resistance to medically important antimicrobials in foodborne pathogens. In aquaculture, the percentage of antimicrobial compounds per survey with resistance exceeding 50% (P50) plateaued at 33% 95% confidence interval (CI) 28 to 37% between 2000 and 2018. In fisheries, P50 decreased from 52% 95% CI 39 to 65% to 22% 95% CI 14 to 30%. We map AMR at 10-kilometer resolution, finding resistance hotspots along Asia's major river systems and coastal waters of China and India. Regions benefitting most from future surveillance efforts are eastern China and India. Scaling up surveillance to strengthen epidemiological evidence on AMR and inform aquaculture and fisheries interventions is needed to mitigate the impact of AMR globally.
In most vertebrates, camera-style eyes contain retinal ganglion cell neurons that project to visual centers on both sides of the brain. However, in fish, ganglion cells were thought to innervate only ...the contralateral side, suggesting that bilateral visual projections appeared in tetrapods. Here we show that bilateral visual projections exist in non-teleost fishes and that the appearance of ipsilateral projections does not correlate with terrestrial transition or predatory behavior. We also report that the developmental program that specifies visual system laterality differs between fishes and mammals, as the Zic2 transcription factor, which specifies ipsilateral retinal ganglion cells in tetrapods, appears to be absent from fish ganglion cells. However, overexpression of human ZIC2 induces ipsilateral visual projections in zebrafish. Therefore, the existence of bilateral visual projections likely preceded the emergence of binocular vision in tetrapods.
There is an urgent need to find alternatives to fish meal and fish oil in compound feeds due to their rapidly rising prices and the demand for sustainable fisheries. Spirulina, a filamentous ...blue‐green microalga, is an excellent source of plant protein and could replace expensive animal‐derived proteins in fish feed. Studies have evaluated the use of spirulina as a fish meal for different fish species. This paper reviews research on the effects of spirulina on the growth performance of various fish species. It is apparent that spirulina can be a highly important component of the diet of fish; it has a number of benefits, such as promoting the growth of tilapia (Oreochromis niloticus) and carp (Labeo rohita), improving the reproductive performance of yellow tail cichlid (Pseudotropheus acei) and enhancing the immune response of rainbow trout (Oncorhynchus mykiss). Recent studies have shown that spirulina can be used for treating wastewater, including effluent from fish culture activities, as it can efficiently metabolize the nutrients and remove the heavy metals contained in aquaculture effluent. Fish aquaculture could apply an integrated strategy of simultaneously treating aquaculture effluent while producing spirulina biomass to supplement fish diets.
The marine ornamental fish trade is expanding and still largely relies on wild fish from tropical coral reef ecosystems. There are unknowns in the wild harvest so that the sustainability of marine ...ornamental fish trade can therefore be questioned with aquaculture being perceived as a responsible alternative for the procurement of these ornamental marine fish. However, there are still many technical constraints that hinder its development. These blocks require additional coordination with the outcome being an accelerated development of ornamental marine fish production. The main objective of this review was to better identify, understand and discuss the role and the impacts of academic research in the production of marine ornamental fish through qualitative and quantitative approaches. To do so, 222 selected scientific publications (including peer‐reviewed articles, conferences articles, thesis and reports) from the literature available to date were analysed and outcomes were framed in perspective of the total number of captive‐bred species. Results of the meta‐analyses indicate that academic research has led to significant advances in the breeding of some of the more difficult to breed species. While it has a leading role in conservation, its advance of techniques still lags behind private companies and hobbyists. Partnerships promoting synergistic activities between academic research institutes and the private sector (aquaculture farms and public aquariums) are important to optimize future ornamental marine fish production.
The neotropical Oscar Astronotus ocellatus has been translocated worldwide as an ornamental fish species with significant economic importance. Twelve adult individuals of A. ocellatus collected from ...aquaria shops in northern and eastern India were examined for monogenean parasites. Based on morphological methods, all fish samples were found to be infested with Gussevia asota, with a 100% prevalence and high mean intensity 30.16 ± 9.70 (18-48, n=12). Molecular analysis of the partial 28S rRNA gene sequence (675 bp), followed by phylogenetic analysis, confirmed the parasite's identity further. This is the first report of G. asota in India and highlights the need to update and strengthen the quarantine procedures concerning the import of ornamental fish.
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