Pharma & Biotech

At ZeClinics, we offer a service portfolio for safety and efficacy studies of new candidate drugs using zebrafish embryos. These assays bridge the gap between in vitro and mammalian models through the preclinical pipeline, in line with the 3Rs.

The main 4 advantages you achieve by using zebrafish embryos for drug discovery are:


Stabulation of zebrafish requires less space and is cheaper than mice because adult zebrafish are smaller and are housed in large groups – up to 70 animals per tank versus only five mice per cage. This is one of the reasons making zebrafish more affordable than mammal research models. In addition, zebrafish pairs produce hundreds of offspring larvae per mating, providing a huge sample size, when compared to rodents. Moreover, larva size is only 5 mm, allowing the use of multiwell plates for separating experimental samples. Finally, drugs are administered in the swimming water, requiring lower amounts of compounds and reducing enormously the time invested in injecting drugs into rodents. All these features allow testing several conditions (different drugs and concentrations) in parallel and, in overall, shortening the experimental time and cost, if compared with equivalent assays in rodents.


Zebrafish larvae are among the most informative, straightforward, and better characterized experimental models. Their optical transparency and ex-utero development, combined with a growing battery of fluorescent tissue-specific transgenic lines, allow direct in vivo visualization of cells, tissues, organs, and embryonic development under different chemical and genetic perturbations to perform simultaneous drug safety and efficacy assays.


Zebrafish embryos represent an ideal model for the screening of large compound libraries and streamlining the drug development process. The small size and a high number of zebrafish progeny allow parallel and reproducible testing of several drugs and dosages in simple multiwell plates and make it ideal for high throughput assays. In addition, the large sample size provides strong statistical power.


Zebrafish and humans have a high genetic homology, as well as high physiological and functional conservation. More than 70% of human genes have a zebrafish orthologue gene. This percentage goes up to 82% when considering human disease-associated genes. In addition, zebrafish show sensitivity, specificity, and accuracy in line with mammalian models. These biological features have positioned the zebrafish as an ideal tool for the study of diseases, biological processes, and drug effects. Indeed, it allows us to assess with certainty the role of a gene in the context of disease and the possible toxicity or effects a compound could have when administered to humans.


The zebrafish model fulfills the purpose of reducing, refining, and replacing the use of experimental animal models. Most of our research is conducted with zebrafish larvae before 5 days post fertilization, meeting the standards set by the European Commission Directive of 2010. The zebrafish model represents a viable alternative that bridges the gap between in vitro and mammal models and can lead to a reduction of animals used in later research phases.

A reliable assay is the key to success at every stage of your drug discovery project. At ZeClinics, we work by your side to boost your research and successfully take your project to the next phase, by meeting your milestones and ensuring compliant, on-time assay results through several stages of your drug discovery process.

Target ID & validation

To correctly tackle a disease and develop efficient therapies, firstly the disease-cause must be identified. Target identification and validation is then a relevant starting point in early phases of Drug Discovery. This process allows characterizing the role of a protein or pathway of interest in order to define the required properties of the compounds to be screened.

For this purpose, whole-body systems are more convenient than in silico and in vitro techniques since they provide complete information about protein interaction and compensation. Genetic manipulations permit a variety of possibilities in target identification and validation but often take very long to give results. 

Zebrafish show great potential in this scenario, since they are amenable to specific and highly efficient mutagenesis and transgenesis, providing in vivo outputs with in vitro inputs.

We have taken advantage of our high efficiency in CRISPR as well as the advantages of the zebrafish to offer quick whole-body target validations within 3 months!

Choose from our approaches for target identification allowing rapid screening of several candidate genes/proteins:

Model generation

Highly specific models that recapitulate the disease or situation of interest are needed to understand the pathophysiological mechanisms, for target identification and for drug screening.

We specialize in generating zebrafish disease models to be used in the preclinical stages of drug discovery. We can develop custom pharmacological-induced and genetic models, with the exact genetic condition and/or the disease-specific phenotypes in order to ease your research. 

Our expertise and know-how in CRISPR and other genetic techniques allow us to develop CRISPR-edited individuals and lines, which can be delivered or used in-house for phenotypic screening.

We offer consulting services to develop tailored-made studies adapted to the specific needs of our clients.

Choose from our disease modeling approaches:


Screening is one of the most initial steps in drug discovery, as one can rapidly identify active compounds. Particularly, phenotype-based screening is one of the most effective approaches to drug discovery.

However, screening was – up to not long ago – only possible with cells as it is a highly automatized process that gives quick results. This has now changed, due to new automatized systems which permit HTS analysis in whole systems.

In this sense, Zebrafish stand out as a valuable system due to their HTS possibilities. Additionally, they permit assessing a specific process combined with a general toxicity assessment of drug screening.

At ZeClinics, we not only have a complete automatized system (VAST), but also highly sensitive software that permits a quick analysis of every zebrafish embryo, divided in 96-well plates. Thanks to these technologies, we can scale our solutions and offer high throughput custom phenotype screenings.

Hit confirmation

Taking advantage of zebrafish's small size, fast life cycle, large-scale progenies, and easy drug administration the activity of compounds can be tested in a high-throughput experiment in a similar way to in vitro testing, reducing time and costs while preserving all the advantages of getting in vivo readouts.

Compounds libraries can be tested in our facility in a short period of time allowing us to support very early stages of drug discovery that are normally precluded to biotesting in vertebrates. Think about zebrafish as a unique tool for hit identification: it is fast, cost-effective, and more informative than in vitro testing.


Zebrafish is the perfect platform for hit optimization and the generation of backups. Quantitative readouts can be analyzed to assess how the chemical modification of substructures can impact the compound efficacy.

Stable genetic zebrafish lines permit correlating phenotypic readouts with target binding (see target validation) making zebrafish a robust tool for the optimization of inhibitors, agonists, and antagonists, and the generation of their analogs.

Moreover, by combining tests from our ZeEfficacy and ZeTox platforms we are able to design tests in which multiple aspects are optimized and improved within the same assay optimizing resources and thus reducing time and costs.


Toxicity analysis

Before the drug candidates are tested in any form on humans, their effectiveness and safety must be proven in vitro and in animals. If the candidates turn out to be toxic or harmful, they won't have a chance for further development. Toxicity screening assays help to determine the presence of toxic chemicals within a drug.

Mammals, which often include rodents, are key animal models used to precisely predict the potentially toxic effects of a drug before entering into Phase I of Human Clinical Trials. However, the use of animal models for testing can be reduced to both follow more ethical guidelines, and save time and money. There are alternative models, like Zebrafish, that are more cost-effective for researchers, while also respecting 3Rs guidelines. Zeclinics offer a wide range of toxicity assays for drug discovery.

Absorption and Distribution Analysis

Drug administration through water incubation is easy but it does not always guarantee a perfect knowledge of the amount of drug absorbed by zebrafish. We set up a protocol to analyze the bioavailability of administered drugs by analyzing the embryos proceeding from toxicity or efficacy assays.

Drug absorption and distribution are analyzed on whole embryos or on specific organs or tissues by mass spectroscopy and liquid chromatography. Moreover, the concentration of compounds in the incubation water can be compared to the concentration in embryos in order to get valuable insights into drug metabolism and excretion. In this case, metabolites, when known, may also be analyzed both in embryos and incubation water.

Our method can be applied downstream to any efficacy or toxicity analysis in our portfolio, on wild-type zebrafish or on genetically modified zebrafish lines with no restriction, providing a useful and inexpensive tool to get insights on the pharmacokinetics of drug candidates.

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